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Beim Kauf des iMac 27" von Ende 2015 war ich nervös, denn es gab nur sehr wenig Informationen zu diesem Gerät. Ich konnte nur ein paar Videos spezifisch zum Teardown finden und sehr wenig Informationen über das Aufrüsten mit einer SSD. Es gab einen Haufen Informationen über das 2014 und Anfang 2015 Modell, aber nichts zum Ende 2015 Modell.

Also, los geht's.

Ich stecke das SATA und das Stromkabel der HDD ab und setze eine 2,5" SSD ein. (Die HDD bleibt an ihrem Platz).

    • Das Öffnen eines iMacs ist knifflig, geht aber mit den richtigen Werkzeugen. Du benötigst einiges Material zum Öffnen des Gehäuses und die SSD korrekt einzubauen.

    • Hier ist ein iFixit Teardown, der dir zeigt, wo du rein musst. iMac Intel 27" Retina 5K Display Teardown

    • Unsere Freunde von OWC haben ein Video, das zeigt, wie die Festplatte entnommen und durch eine SSD ersetzt wird. Diese Anleitung hier zeigt dir aber, wie du die Festplatte einfach lassen und eine SSD dazufügen kannst. https://vimeo.com/139364064

    • Benutze zum Öffnen gute Werkzeuge, wie z.B. Pro Tech Toolkit and Jimmy Ich selbst habe ein Skalpell benutzt, ich fand ein Plektrum zu schwach. Mit einem Jimmy müsste es auch gut gehen.

    • Du benötigst auch den OWC In-Line digitalen Thermosensor. Damit kann der iMac weiterhin die Temperatur kontrollieren. Anderenfalls werden die Lüfter mit Höchstdrehzahl laufen. Dieser Reparatursatz enthält auch das notwendige Klebeband. https://eshop.macsales.com/item/Other%20...

    Can you use SSD Fan Control app to keep the fan at the normal speed?

    A VIEW - Antwort

    Why would you want to? Just use the thermal sensor and the fans will stay in check, no need for a piece of software. https://eshop.macsales.com/item/Other%20...

    Justin Winchester - Antwort

    So this guide basically shows you how to install a regular non Apple SSD in a imac that already has a “fusion drive”?

    So now you have the hdd that was not moved and the Apple pcie ssd and now the new non Apple ssd right?

    gleeglee217 - Antwort

    Correct. The big take away is that I didn't have to move or remove anything. I was able to add my own SSD, and use Apple's built-in SSD. However I did lose the 2TB Fusion drive, and I'm not the least bit sad about that.

    Justin Winchester -

    Thanks for the guide, One question though. Did you find or have experience any issues being the fusion drive still in there? Not sure how the two SSD's would behave and work, but i want to make sure there are no conflicts between them. Also, I am assuming you must have seen lot of improvements in terms of performance, read/write, speed etc after the SSD replacement, right? Mind sharing the before and after if you have recorded something?

    Mohit S - Antwort

    The fusion drive is completely disconnected, so it does nothing but take up space.

    Modern computer can handle multiple drives, doesn't matter their type. The SSD are two different drives so the iMac just mounts as such. The iMac (or any computer) can really handle as many drives as you could connect to it, internally, or externally. So no there would be no conflicts between SSDs, HDDs or any mix thereof.

    Yes, SSDs are insanely faster and better in every way. I did not run any benchmarks because I never even booted this iMac with the Fusion drive. I installed the SSD before I even booted it up for the first time. But you can look up any benchmarks for my SSD vs a standard WD 7200RPM drives

    Justin Winchester -

    In Justin’s case, the boot time would probably not change all that much since the operating system is effectively on the ssd part of the “fusion drive.” The big performance improvements will start to show up when you put more than 128 GBs of data on your system.

    Rick Harman - Antwort

    Can someone explain why the existing hard drive doesn’t need the OWC thermal sensor? Why can’t you just disconnect the cables from the HDD and reconnect them to the replacement SSD?

    Copywriter Ben - Antwort

    This config just leaves the HDD in place unused, Instead of removing it. All you are doing here is saving a few bucks for the 2.5” to 3.5” adapter frame and fully removing the HDD.

    The original Apple HDD has a build in thermal sensor which Apple leverages. When you replace the drive with either a HDD or SSD you need to replace the now missing sensor Apple uses to manage the systems cooling. Thats why you need to add the OWC in-Line sensor.

    Dan -

    As Dan stated, any drive other than Apples requires the thermal sensor. And yes it only saves you a bit of money ($15 dollars) but it saves you A LOT of time, makes the SSD addition WAY easier, and you are FAR less likely to damage your iMac since you don’t have to remove any components.

    Justin Winchester -

    Bonjour, question de novice mais peut-on ajouter plutôt un SSD M2 sur l’iMac 27" (fin 2015) ? Avec la même procédure ?

    Vincent - Antwort

    No you cannot.

    Justin Winchester -

  1. Bei den aktuellen Anleitungen von iFixit und OWC werden die Displaykabel abgelöst. Bei dieser Anleitung hier ist das nicht nötig.  Ich habe meinen iMac waagerecht hingelegt und dann das offene Display einfach mit zwei ganz normalen Bleistiften auf zwei Seiten abgestützt.
    • Bei den aktuellen Anleitungen von iFixit und OWC werden die Displaykabel abgelöst. Bei dieser Anleitung hier ist das nicht nötig. Ich habe meinen iMac waagerecht hingelegt und dann das offene Display einfach mit zwei ganz normalen Bleistiften auf zwei Seiten abgestützt.

  2. Hier kannst du sehen, wie ich das SATA Kabel von der Festplatte abgelöst und das OWC Thermosensorkabel angeschlossen habe. Auch die SSD ist schon angeschlossen. Das OWC Kabel ist ein wenig steif, ich musste es ein bisschen verdrehen, so dass die SSD flach im Inneren des iMac liegen kann. Diese Einbuchtung, wo du die SSD sehen kannst, ist normalerweise leer und der perfekte Platz für eine dünne SSD.
    • Hier kannst du sehen, wie ich das SATA Kabel von der Festplatte abgelöst und das OWC Thermosensorkabel angeschlossen habe. Auch die SSD ist schon angeschlossen.

    • Das OWC Kabel ist ein wenig steif, ich musste es ein bisschen verdrehen, so dass die SSD flach im Inneren des iMac liegen kann. Diese Einbuchtung, wo du die SSD sehen kannst, ist normalerweise leer und der perfekte Platz für eine dünne SSD.


    where did you connect the SSD cable? Does this work on late 2015 imacs & do I need the thermal cable on 2015 models?


    Beni - Antwort

    You have to buy an iMac with the fusion drive option and I took that cable and attached my thermal cable and SSD to it. As stated in the guide, yes you need the thermal cable.

    Justin Winchester - Antwort

    thank you for the response

    Beni -

    What if I bought an iMac with SSD only. Will I be able to add another SSD to where the HDD is location for the fusion drive models?

    Ken Lu - Antwort

    Ken, no you cannot. As Apple does not ship the SSD only iMacs with the SATA cable in place. But if you buy the fusion drive you still get the 128 on board SSD after detaching the fushion drive.

    Justin Winchester - Antwort

    Thank you for the response, but can I just use my own SATA cable or is there no such plug for another SSD on the logic board?

    Ken Lu -

    You "can" but it would be a HUGE pain, as you'd have to remove everything out of the case since the plug for the SATA connection is on the backside of the MoBo. And from what I've read it appears to not just be a standard SATA cable.

    Justin Winchester - Antwort

    So you said you detached the sata cable from the hdd and attached it to the new ssd then how would the hdd function communicatting to the mother board? Or do you mean that the hdd will no longer work?

    Also is it safe to attach only Apples sata cable and no owc thermal sensor cable? After insatlling the ssd and If the fan is not always on high then there is no need for the owc cable.

    gleeglee217 - Antwort

    In step six you can see that I say that "That's it! I can't use the 2TB HDD, but I was able to install an SSD with minimal effort and risk without removing the display, disconnecting the display cables, or removing the speaker, or HDD."

    I didn't want or need the HDD in the first place, so I didn't mind the loss.

    No you need the OWC thermal cable as well, or I wouldn't have added it to my guide... You need that whenever you install a non-Apple drive in a machine.

    Justin Winchester -

    Hi, thanks for posting this. I’ve an iMac Retina 5K, 27-inch, Late 2015, 3TB fusion. Can I add a NVMe M2 SSD instead of the SATA. I assume that there’s an adapter somewhere that would allow me to connect it to the existing SATA cable

    Simon C - Antwort

    I don’t think so. Even if there was an adapter you would lose all the benefit of an NVMe drive, which is it’s speed.

    Justin Winchester -

    NVMe requires a PCIe connection not a SATA connection.

    Dan -

  3. Als nächstes habe ich den Thermosensor an der SSD angebracht und dabei die Kabel so ordentlich und kompakt wie möglich gehalten.
    • Als nächstes habe ich den Thermosensor an der SSD angebracht und dabei die Kabel so ordentlich und kompakt wie möglich gehalten.

    • Ich habe die SSD an dieser Stelle mit einigen Klebepads von 3M befestigt. Genau an dieser Stelle ist der iMac ein wenig gekrümmt und ich brauchte etwas Dickeres als die üblichen Klebebänder. https://smile.amazon.com/dp/B00O1WFF8U

    • Ich habe insgesamt vier dieser Quadrate in Doppellagen verwendet. Je einer dieser Doppeldecker befindet sich hinten links, der andere vorne rechts.

    1. Is the temperature sensor necessary to attache ?

    2. Is there a specific place to attach the sensor on the SSD ?

    3. Is this temperature sensor fits the iMac 5K - Mid 2015 http://a.co/j9WAyZY ?

    Abdullah Algarni - Antwort

    - Yes you need the sensor.

    - Any spot will work.

    - That looks to be the wrong sensor. Use the one I've listed above: https://eshop.macsales.com/item/Other%20...

    Justin Winchester - Antwort

    Is the temperature sensor as pictured right above different than the OWC thermal sensor? If it is diff then was it unplugged from the hdd?

    gleeglee217 - Antwort

    @gleeglee217 The temp cable is the OWC cable. You only buy the cable if you are using an SSD, so it would never have been plugged into the HDD.

    Justin Winchester - Antwort

  4. Zum Abschluss habe ich das Thermosensorkabel mit einem Kabelbinder ordentlich an der Festplattenhalterung befestigt. Ich wollte auch das OWC Kabel so weit wie möglich vom Display entfernt halten. Auf dem zweiten Bild kannst du sehen, dass noch genug Platz ist; das OWC Kabel und der Kabelbinder sind weit genug unter der Festplatte und dem Abluftkanal.
    • Zum Abschluss habe ich das Thermosensorkabel mit einem Kabelbinder ordentlich an der Festplattenhalterung befestigt.

    • Ich wollte auch das OWC Kabel so weit wie möglich vom Display entfernt halten. Auf dem zweiten Bild kannst du sehen, dass noch genug Platz ist; das OWC Kabel und der Kabelbinder sind weit genug unter der Festplatte und dem Abluftkanal.

  5. Das war's! Ich kann zwar nicht die 2 TB Festplatte benutzen, könnte aber mit kleinem Aufwand eine SSD installieren, ohne Display, Displaykabel, Festplatte und Lautsprecher zu entfernen.
    • Das war's! Ich kann zwar nicht die 2 TB Festplatte benutzen, könnte aber mit kleinem Aufwand eine SSD installieren, ohne Display, Displaykabel, Festplatte und Lautsprecher zu entfernen.

    • Als Bonus kommen die Festplatten des iMacs als "Fusion Drives", haben also auch eine PCIe SSD. Meine hatte eine von 128 GB, die kann ich jetzt als weiteres Laufwerk nutzen. Ich plane, darauf Windows über BootCamp zu installieren.

    Hi, I’m looking to buy a late 2015 model and I had the same idea you did. After switching the HDD with a SSD drive I would like to use the Fusion Drive’s PCIe (128 GB) for Windows. However, I read that the iMac will always install macOS on the small SSD blade. Is this true? What did you end up doing?


    Nicolai - Antwort

    As you can see by the end of my guide, that is exactly what I did. I used the 128GB PCIe drive for Windows 10. Once you replace the HDD you break the Fusion Drive “link” so that both drives show up in Disk Utility. So then your can Independently format and install any OS you want on the SATA or PCIe drive.

    I never even turned my iMac on when I bought it, I went straight to adding the SSD. So after I added the SSD I then formatted the SSD and the PCIe blade. So I don’t know what was on the PCIe blade, but it doesn’t matter what it has since it’s very easy to format and install Windows/macOS on it. I just formatted my PCIe blade and ran Boot Camp to install Windows 10.

    Justin Winchester - Antwort

    As you can see by the end of my guide, that is exactly what I did. I used the 128GB PCIe drive for Windows 10. Once you replace the HDD you break the Fusion Drive “link” so that both drives show up in Disk Utility. So then your can Independently format and install any OS you want on the SATA or PCIe drive.

    I never even turned my iMac on when I bought it, I went straight to adding the SSD. So after I added the SSD I then formatted the SSD and the PCIe blade. So I don’t know what was on the PCIe blade, but it doesn’t matter what it has since it’s very easy to format and install Windows/macOS on it. I just formatted my PCIe blade and ran Boot Camp to install Windows 10.

    Justin Winchester - Antwort

    Hey Justin, thank you for your quick response and the great guide! Plan to do the same with the knowledge from you!


    Nicolai - Antwort

    Just ordered the adhesive strips and will be performing the install next week :-)

    RAVI M. - Antwort

    • Für den allerletzten Schritt musst du das doppelseitige Klebeband in der äußeren Rille des iMac ersetzen. In Schritt 1 habe ich schon das 3M Band zusammen mit dem Thermosensor aufgelistet

    Because you did not completely remove the display, did you leave the old tape along the bottom edge? It seems with the approach you are using that it would be harder to clean up the old tape and install new tape.

    Graham Wheeler - Antwort

    Correct. I only replaced the tape on the top and sides. I did not cur or remove the tape on the bottom, no need to.

    Justin Winchester -

    I used the OWC tape on a 2012 SSD upgrade. A week later I was mortified to learn from the customer that the screen came away from the casing while he was using the machine. Luckily he caught it and put tape on the top outside to stop it happening again. Not what you want to hear when your reputation rides on your work.

    Now I’m left wondering if I should chance it again on another machine I need to do or go with some thicker 3M stuff. Is the 3M stuff easily cuttable if the machine ever needed to be opened again?

    I’m thinking the adhesive warms up and loosens when the machine is under load? Worried.

    Cool_Breeze - Antwort

    Don’t use any other tape as then you’ll end up breaking or damaging the display the next time you take the display off!

    The process of cleaning the surfaces has a big bearing on how well the tape adheres. To add to it that the temp of the case and display as well as the application of pressure is also important. You want the case and the glass to be warm and you also need to press the display glass down using a J roller.

    As a habit I also dry fit the display to make sure the case is not warped as that can cause the display to pop off! Make sure the taped are in an air tight bag (burp the air out if you have a few sets inside). Use reagent quality 95% or better isopropyl alcohol as the cheap stuff has other junk in it which will interfere with the adhesion. And most important is to make sure you’ve removed all of the old adhesive. I’ve easily done over 500 systems by now, while I did have some issues at the start I’ve not had any issues for years!

    Dan -


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120 Kommentare

Hello, in the last part of closing the iMac, what is the adhesive that you use? I bought some on ebay but its not strong enough. thanks.

PCosta - Antwort

My link was in the post: https://eshop.macsales.com/item/Other%20...

It includes the thermal sensor and the tape.

Justin Winchester -

If you are installing an SSD to replace the HDD on iMac 2013 and later, you don't even need the thermal sensor cable from OWC because the heat info will be read through S.M.A.R.T. I think that OWC thermal cable for iMac 2013 and later is a scam. The reason why you need the thermal sensor is that Seagate HDD has a proprietary thermal port back in 2010. The thermal info cannot be read by SMART back then. The new iMac from 2013 (probably 2012 included) will no longer need the thermal sensor cable.

Evan - Antwort

Well, unless someone has a definitive answer on if it's needed or not I'd still recommend it. Plus it comes with the tape needed to secure the iMac.

Justin Winchester -

Doesn't the newly installed SSD block the fans natural airflow path being placed there?

chrisrayrobertson - Antwort

@chrisray No. The new 5K iMacs have the external fan hole coming out the center of the back of the case. The older iMac's had a thin vent that ran horizontally along the top third of the back case, and that might have been blocked. But on the 5K iMac the plastic fan in the middle pushes air straight out that vent on the back. The SSD does not impede on that at all.

Justin Winchester -

When you set the iMac back upright, do those adhesive squares actually hold the drive in place or does the drive end up resting on the screen slightly? You work seems great just curious if this will impact the screen life.

John - Antwort

In fact, I tried to move the SSD a bit and the tape held it so good I couldn't get it off the case with moderate force. I used four adhesive squares, but in only 2 spots (stacked then on each other) and the hold is extremely strong, I'm not worried about that drive going anywhere.

Justin Winchester -

Isn't there an option to have both the Fusion drive AND the SSD connected?

mauricehason - Antwort

No. Apple uses a special SATA cable to connect from the logic board to the drive. I'm not sure if there is even another spot to connect a second drive, even if you could get your hands on this Apple cable. However, with the fusion drive option you do get a built-in SSD drive. Mine was 128GB. So basically I now have 2 SSD's connected to the iMac.

Justin Winchester -

Great guide man. Did exactly as you've done and worked great. Took less than 20 minutes start to finish for the swap. I didn't have pencils..lol..used a water bottle.

Ron Ramkirpaul - Antwort

I have the late 2015 5k iMac for 2 months now. I really want to add an SSD for my main drive, this Fusion Drive is terribly slow. This is soo scary

Gino Brugman - Antwort

If you've never opened a computer before it can seem daunting. But this guide is really pretty easy since you're not removing or even moving an existing parts. The hardest part is attaching the tape strips to secure the display in place. Opening and adding the SSD is the easy part.

Justin Winchester -

Is it possible to fuse the PCIe SSD and the new SSD drive into a “fusion drive”? My fusion drive has only a 24GB SSD so it wouldn’t be useful for much.

BixbyConsequence - Antwort

No. A “Fusion Drive” is just a software trick by Apple. They move frequently used programs over the the SSD and off the HDD. Having two SSDs means you don’t have a bad drive.

But I think what you’re really asking is you like the Mac to see them as just one drive, but now there’s not really a good way to do that with how small it is.

Justin Winchester -

Thanks Justin. My understanding is the small internal SSD is NVME storage, which is still much faster than an ordinary SSD. But you’re right, my biggest concern is I just don’t want a 24GB drive hanging around and I’d rather not tear down the machine that far just to remove the NVME card.

BixbyConsequence -

wtf? lol why not just use a 2.5 to 3.5 adaptor and take out the hdd so you can use it as a docked external? seems really shoddy doing it with tape mate

Daniel Browne - Antwort

If you read the guide you would know why. The whole point of this guide is to AVOID removing the OEM HDD. It’s a huge pain and requires removing several difficult components. I have plenty of external HDD laying around and don’t need an extra one. If you want to spend the time and risk, removing the screen, speaker, fan, etc. go ahead. But they is a much smaller risk in my method of barely opening the case, not removing anything, and simply placing a small SSD inside and securing it with strong 3M tape. This is a desktop that should never move, so there is little to no risk to it moving. And if it did it would fall straight down on the HDD causing no issues.

I’ve taken dozens of iMacs and MacBooks apart and concerted the HDD to SSD with 2.5-3.5 converting brackets. But with these new thin iMacs this is by far the best, easiest, and safest method to open and upgrade an iMac.

Justin Winchester -

Hi! I've been using an iMac 27 mid 2011 with 2 drivers. I upgraded the original HDD for a new 4TB HD and add an SSD as primary drive. With this configuration I have installed the O.S. on the SSD and the large files (photos, videos, etc…) is stored in the hard drive. I love this configuration because I have speed and great storage space without external devices. I decided to upgrade to an iMac 27 5K Late 2015 A1419 3.2Ghz and I want a similar solution, SSD for the O.S. and a large HDD for files, everything inside the iMac. I saw in this post that is possible to keep both devices inside, but there is a way to use them at the same time? Apparently there is no conector on the logic board for a second drive, but there is any way to make this happen, like an adapter for the logic board fusion drive conector? My iMac came with a 1tb Hard Drive (NO FUSION DRIVE). Can I upgrade this hard drive for a 4TB and buy a SSD similar as Apple uses as Fusion drive and install it? 256 or 500gb will work fine for me. Thanks!

Michel Monteiro - Antwort

No, you can’t have two SATA drives running in this system. You need to have a PCIe blade drive and SATA drive. Then you can get this config.

Dan -

Hey Michel, so the 2015 has two connections for drives. If you get a “Fusion Drive” option, they give you two separate drives, an SSD and an HDD, Apple just makes them act as one. So you have a SSD that sits in an mSATA port that is super difficult to get to and then a standard HDD, that you can get to easily as you can see from my guide here.

So to do what you want you’ll need an mSATA SSD (256GB/500GB) and then your 4TB can replace the standard HDD.

Justin Winchester -

Thanks @danj for the reply. And what types of PCIe blade does the iMac 27 5K Late 2015 A1419 3.2Ghz  supports?

Michel Monteiro - Antwort

The best thing is to buy a SSD only system and then add the HD. But keep in mind you’ll void your warranty. So wait awhile until your sure the system is solid before doing this and review the IFIXIT guides on whats needed and how. I must warn you taking the display off is a bear if you don’t user the correct tools and techniques. If you don’t do it correctly you can damage the display and that would be an expensive Oops!

Dan -

@danj I already bought an used iMac 27 5K Late 2015 A1419 3.2Ghz. The screen is already broken, the first owner did a normal SSD upgrade (the iMac originally came with 1TB HDD) and damage the screen in the process. That's why I want to know what blade model is compatible, because the iMac does not have any Blade. (do you know if the mother board has the blade conector?) I'll replace the screen and want to do the storage upgrade after remove the broken LCD. I would like to have SSD 256 or 512 and a 4TB hard drive. Just my Photos library has 1.2TB, Lightroom 1TB, Final Cut 1TB so this library's and my personal files will be stored in the HDD, and the O.S., programs (Final Cut, Pages, Photoshop, etc..) will be stored in the SSD for performance. I already have this configuration on an 2011 iMac 27” and worked great for me. I personally don't like external devices because of my desktop space, so if you have another suggestion I'll appreciate. I also have a QNAP TS453A for Plex, backup and others files. Thanks.

Michel Monteiro - Antwort

You should post your question in the https://www.ifixit.com/Answers forum to get more visibility. You might even find other questions like yours there that might give you some ideas.

Dan -

Hi Justin

Great post! I just got a late 2015 and plan on upgrading like you did. My question relates to the remaining SSD on the Logic Board. Does it basically still work as if the new SSD was the old HDD?

When you said you have access to the original SSD as an extra drive, do you mean that you can use it separately from the new SSD?



Ricardo Blanca - Antwort

Once you swap out the HDD included as part of the “Fusion Drive” then yes they act as two separate drives. You can see in my screen shot I have the included SSD a 128GB and the SSD I added that is 750GB. Both function as two separate drives.


Justin Winchester -

Thnx for the stuff !! I have late 2015 Imac 27” its with normal Sata HDD of 1 TB. I plan to use a 512 GB SSD as primary . Is there any issues or possibility to use both Sata HDD and SSD.



anubhav verma - Antwort

There is not a way to use two drives unless you get the fusion drive option and use the built it SSD (like I did) as one of your drives.


Justin Winchester -

@jayman16 , Did you have to remove the adhesive on the bottom part as well? I see that you didn’t open it all the way.

Did you have to install the OS before putting the SSD? Thx

Richard Lung - Antwort

I did not remove the bottom adhesive. That’s one of the best parts of my method because you don’t remove the whole display so it stays perfectly lined up. Which is hard to do when the display is all the way off.

Justin Winchester -

@jayman16 that makes sense. How’s the EVO working for you? I asked a tech shop and they said the EVO isn’t compatible with iMac ( The S.M.A.R.T status was not working) so you couldn’t tell the SSD health status. They recommended OWC drive.

Richard Lung - Antwort

While they may be true, I’m unsure, it’s never been a concern of mine. With my iMac or any of the countless Mac’s that I’ve upgraded with EVO’s in the past. SMART is more of a Windows thing anyway, I’m not even sure if macOS uses it.

Justin Winchester -

@jayman16 did you have to unlink the fusion drive first or no? Also, did you try to create a fusion drive to merge both SSD after? Thanks!

Richard Lung - Antwort

The “Fusion Drive” is all done inside of macOS, there is no user facing setting for it. So no, I never unlinked or linked them together.

Justin Winchester -

Compared to sata , do you feel the performance has increased? i m an editor photo and video hence wanted to know the same

anubhav verma - Antwort

Oh my god, yes. An SSD will give you vastly increase speed and performance over any other upgrade you could do. RAM, CPU, GPU, etc. Going from a HDD to a SDD you’ll see 10-20X in speed boost.

Justin Winchester -

Thanks for this guide. I’ve already purchased the SSD and now about to place orders for the existing tools needed.

Is the Pro Tech Toolkit you have listed here at all necessary? It’s rather expensive, and if it’s not needed (which it doesn’t really look like it is), then I’ll just get the jimmy or some other tool used for opening up the iMac.

Also, what is the risk of wrecking the screen when cutting through the adhesive tape? I saw a guide where someone used a) a guitar pick (as you mentioned) and b) a bookmark. I am concerned that if I dig “too far” past the adhesive that I will do some damage to the screen, etc. I’ve never done anything like this before so perhaps I’m just being overly cautious, but I really don’t want to screw anything up.

Thanks in advance.

Michael Kuby - Antwort

Thanks for the question.

So no, you really can’t go too far. I mean, you “can” but you won’t. You got almost a 1/2” clearance on left/right/top. And there are no sensitive LCD parts in your way. The only thing to be wary of is the front camera at the top middle.

As as far as tools. You just need the Jimmy and some torx bits. The pro tool set gives you everything you’ll need and more. It’s great to have. But you can get by with a small set or just the torx bits you need. 6 and a 9 IIRC.

Justin Winchester -

I purchased my iMac 5K with a 500GB SSD only. Does that mean that the HDD space is empty (but still with appropriate cables) and I can put a second SSD in it’s place leaving the original in there (which I think is a blade SSD or something).

Andrew Waters - Antwort

Yes, the regular SATA HDD space is empty. The issue is the cable, its a special cable that is hard to find/expensive AND the connection port on the logic board is on the front of the board. So you’d have to remove the entire logic board to be able to plug that cable in. When I was researching this model that is why I bought the Fusion Drive so I wouldn’t have this issue. Hope that helps.

Justin Winchester -

Hi Justin, thanks for the great guide.

I will follow you step by step as it seems really easy and straight forward.

I’d like to ask you a question though regarding the cloning of the entire system.

I have an Imac 27 retina 5k late 2014 with 1TB fusion drive. I read somewhere that before cloning the entire system into the new ssd I have to split the fusion drive.

- What does it mean?

- How did you clone the entire system from the HDD to the new SSD? What I want is just to copy everything into the new SSD hoping that the performance of my computer increases.

Thanking you in advance


Matteo Branca - Antwort

You performance will certainly increase 10x or more.

- My iMac was a brand new machine and had never been turned on prior to my “surgery”. I pulled the SSD out of my old iMac and simply installed in and turn the new iMac on.

- I’m not sure what you read about “splitting the drive” I’ve never heard that or ran into any issues. I’m assuming it has to do with the fact that the Fusion drives act (and look) like one drive even though they are two.

- However, you have several options to move from the HDD to an SSD.

1. Use Apple’s Time Machine program to backup your current HDD to an external HDD and then install a clean copy of macOS on the new SSD and the use Migration Assistant to bring everything over.

2. Easier would be to just get an external enclosure and plug in your SSD into your Mac and use a program like SuperDuper! or CarbonCopyCloner to copy your current HDD directly to the SSD. Then swap the HDD for the SSD and it should boot like normal, just WAY faster.

Justin Winchester -

Why did you leave the HDD in the iMac? Take that sucker out and use it as an external drive or sell it on ebay!

Yes, it’s more disassembly, but you’ve already done the hard part by cracking open the screen from the body. It’s not risky unless you’re technically challenged, in which case you shouldn’t open your iMac up anyways.

For those who are comfortable handling CPUs and thermal paste, this is a good opportunity to upgrade the CPU unless it’s already the top option for your generation iMac.

rgiskard - Antwort

First, this is guide is explicit on ADDING a SSD not to replace a hard drive.

I left in the HDD because it would turn into A LOT more work. You would have to take to display completely off, which I did not do and makes it a lot more risky of an operation. They move all the other parts like the speaker, fan, etc. All for a $50 hard drive? No thanks. Sell it on eBay? For what $35-$40 and deal with shipping it, don’t need that hassle to make $35 bucks. Keep it maybe, but I’ve got plenty of drives floating around, and I much prefer 2.5” drives that are bus powered and don’t need an extra power source.

But the main reason is, that is the original HDD intact from Apple, never touched or used. So when I go sell this iMac, I just pull out my SSD and hookup the HDD and the buyer has brand new HDD with a clean install of macOS.

The level of users that use these guides range in skill, and I think it’s not fair to say that novice users shouldn’t be opening their Macs, everyone has to start somewhere.

Justin Winchester -

Can I do this upgrade on an HDD iMac (without fusion drive) to improve the speed of the computer?

Merlin Hibbs - Antwort

You could, absolutely. But I believe all the drives in the 27” 2015 models are either Fusion or SSD.

If if you have an older iMac with just a regular HDD then yes it will give you 5-10x speed increase for swapping the HDD for a SSD. You will still need the drive bracket and thermal sensor.

Ive updated over a dozen iMac’s and installed SSD’s to replace HDD’s. Best thing you can do to get a faster machine and give it a longer life.

Justin Winchester -

According to the https://everymac.com/systems/apple/imac/... “This model is equipped by default with either a 1 TB (7200 RPM) hard drive (MK462LL/A) or a 1 TB "Fusion" Drive, which combines a 24 GB SSD and a 1 TB hard drive (MK472LL/A). It has a Serial ATA (6 Gb/s) connector for a 3.5" hard drive.At the time of purchase, Apple offered a 2 TB "Fusion Drive" (which combines a 128 GB SSD and a 2 TB hard drive) for an extra US$200, a 3 TB "Fusion Drive" (which combines a 128 GB SSD and a 3 TB hard drive) for an extra US$300, a 256 GB SSD for an extra US$100, a 512 GB SSD for an extra US$400, or a 1 TB SSD for an extra US$900.”

Gabriel Voican -

Yes! Your system has two drive ports, either replacing the SATA HDD for a SSD or you could add in a PCIe/NVMe blade drive which offers even more performance. Adding the blade SSD allows you to gain a dual drive setup. What gets people confused is the Fusion Drive setups, while it is also using a small blade SSD, this setup us using the SSD as a cache drive not a straight drive! Here we are using a large drive and setting it up as the masOS boot drive and only using the HDD for your data drive!

Dan -


Hello. Thank you very much for the tutorial.

Is it possible to use a sata duplicator cable and put two SSD drives?

João Paulo - Antwort

I don’t believe so. Apple uses a proprietary SATA cable, so I don’t think you can swap it out or extend off of it.

Justin Winchester -

My Late 2015 27 came with a 2.5 ssd only. I want to replace that with a 4TB 2.5 hdd and add a 512 M.2. Do I need the thermal sensor for the 2.5 hdd?

Steven Van - Antwort

This all sounds like a bad idea, and difficult.

If it only came with the SSD drive then it’s on the inside of the logic board and very difficult to get to. You have to take EVERYTHING out of the case. And the SSD connects via PCIe not M2. Also to add a HDD (or SSD) to the front as I have, you have to have Apple’s proprietary SATA cable. Since yours only came with the SSD you won’t have that cable and will have to add it. That SATA cable also connects on the inside (between logic board and screen) and requires removing everything to get to it.

No matter what you do, I would in no way add an HDD. And if you did, yes you would need the thermal sensor cable. Personally, I would either upgrade the PCIe SSD that is there or add a second SSD drive. If you add a HDD I believe you would have to install macOS on it, thereby making your SSD worthless since the OS would be running off the HDD.

iMac Intel 27" Retina 5K Display Teardown

Justin Winchester -

I cant “upgrade” the pcie ssd, there is none, only a sata ssd. Ive taken apart a half dozen imacs and they are not that difficult to work on. You have to take EVERYTHING out . everything consists of a lcd panel, hard drive, a fan a power supply and speakers a bunch of screws and a few ribbon cables. Apple can change its proprietary connection every year if they like but most understand its just their version of m.2 in this case pcie m.2

Steven Van - Antwort


Awesome guide - however, how can I know what size the NVMe part of the fusion drive is? If it’s less that say 100 gigs, I’d rather exchange the whole part, or maybe buy an iMac with built in SSD (and then I can use the HDD slot for a second SSD, right??)

Haven’t bought an iMac yet, still trying to figure out what model to choose.


Jan - Antwort

I believe they are normally 128GB. However getting to the NVMe part is EXTREMELY difficult, and not worth trying to replace. IMHO. That’s why my guide was about avoiding getting to it. A lot more risk involved.

I did a lot of research on the iMac before I bought mine. If you buy an SSD iMac then they do not have the HDD nor the SATA cable installed that I used to connect my SSD. And this SATA cable is an Apple built cable for the iMac so it’s not easy to obtain. The fusion drive is the best option because then you get the SSD and the HDD drive.

Justin Winchester -

I almost pulled the trigger on this with my late iMac 2015 with 2TB Fusion. And I compliment you on a much easier solution to add a SSD with many less steps.

But my concern is I now have to manage 2 separate drives vs the current 1 drive. My 128GB blade gets 600+ Writes and 1600+ Reads, the new drive will be around 500GB/s R/W.

I did de-fuse my drives once when I first got it, but it was a bit of a pain using symlinks and I ended up fusing them back.

If I only had a 1TB fusion with the 24GB blade it would be an easy decision and I would not even use the blade.

What speeds are you seeing from your 840 Evo and how are you managing your file system with 2 drives?

ktf6768 - Antwort

I haven’t done a speed test in a while, so I can’t remember I’ll have to check. As far as file management, my factory 128GB SSD I use for Windows 10 via Boot Camp. My 840 EVO is just my regular OSX drive.

What I would recommend is that you just treat the 128GB SSD as just an extra drive, a bonus. Just use a big enough main SSD that you don’t need the built in drive. But it’s there if you ever need it.

Justin Winchester -

Has anyone performed Justin’s mod without the thermal sensor? Thanks!

Rick Harman - Antwort

It won’t work. Your fan will continue to spin at full speed without knowing the temp.

Justin Winchester -

If i want to change only ssd (blade)with bigger size can i leave hdd there just unplug the cables?

Aram Manukyan - Antwort

@Aram Are you taking about changing the internal SSD for the Fusion Drive? If so then, it’s a HUGE pain to get to. My method left the internal SSD in place and just simply replaced the HDD by using the HDD cables for a new SSD.

Justin Winchester - Antwort

Hi Justin, first thank you so much for all the help you provided here so far.

It looks like someone already asked this question but I didnt get the answer to be frank.

I have the iMac 27’’ Late 2015 with 1 TB Fusion Drive, am I able to install a new 500GB SSD to run the OS, but at the same time have the 1 TB Fusion Drive remained installed and usable? Meaning 2 drives, one for storage and one to run the OS. Thank you so much.

Joao A - Antwort

If you have a Fusion Drive Mac then you really have two drives, an m.2 SSD that is on the backside of the logic board and EXTREMELY hard to access and change. Then you have a standard HDD as shown in my tutorial that is very easy to get to.

If you install an SSD with my guide here, then you will lose access to the 1TB HDD that came with the system. There is only one cable that comes around the front of the logic board and in my guide we take that SATA cable from the HDD and use it in the new SSD.

You *could* replace the built-in m.2 SSD with a bigger drive, but I can’t stress how much more difficult it is to get to. Then you could keep the 1TB HDD. My advice, is to simply replace the 1TB HDD with as big an SSD as you need. Wait and save money if you need to. Trust me you don’t want to have a HDD involved at any point in your system, all it will do is slow you down.

Justin Winchester -

Hi Justin, thanks for a great guide. I have a 2017 iMac with fusion drive and I am considering using this guide to install a 1TB SSD. It all seems very doable with the right tools, the only thing I am worried about is the adhesive. Having the iMac propped open like you do, is it easy to remove the adhesive on the sides and top and is there enough space to line up the new adhesive strips? ( I am assume the bottom adhesive isn’t broken and should be left untouched)

albertbonder - Antwort

You’re correct. The bottom adhesive stays in place. It’s easy enough to remove and replace the top and side(s) adhesive.

Justin Winchester -

Hi Justin,

Did you have to initialise the SSD drive with Macosx? or does the iMac comes by default with MacosX installed on the Internal SSD drive?

josé - Antwort

macOS is installed on the HDD. macOS slowly moves data over to the SSD depending on usage. So if you use Photos.app a lot, it moves it to the SSD. So by default the SSD basically has nothing on it. So to use it you’ll need to format it and install macOS (Or Windows like I did) to use it.

Justin Winchester -

Do you think that this SSD would work OK? I would be good to know which SSD HDD would work in this way? Do they all just use the same power etc? https://www.amazon.co.uk/Seagate-BarraCu...

Simon Taylor - Antwort

This guide is merely disconnecting the 3.5” SATA HDD drive placing the 2.5 SATA SATA drive just above it. Any SATA SSD with work here. You might want to review the performance of the Seagate drive here Seagate BarraCuda SSD Review

Dan -

Hey Simon,

It will work fine. An SATA drive will work. But I would highly recommend the Samsung 860 Evo for performance and speed. https://www.amazon.co.uk/Samsung-MZ-76E1...

Justin Winchester -

Thanks very much Dan & Justin. Very sorry for the delay in my response, I expected I would receive an email from iFixit if there had been a reply. The performance of the Samsung looks way better - I will be going for that one.

This weekend’s work sorted, clean install of MacOS and we should have a much faster computer.

Simon Taylor -

A few questions: I have a late-2015 27” iMac 5K equipped with factory-installed 500GB SSD (Physical Interconnect: PCI; Model SM0512G; Revision BXW5TA0Q; SN S2P9NYAGA00439).

I want to increase the internal storage to 2 TB SSD. What I’m confused about is whether the current configuration uses a “blade” SSD. And if so, whether I could (or should) leave that alone?

This SSD upgrade kit seems to indicate it’s configured with a 2.5” SSD — not a “blade” SSD:

iMac Intel 27" (Late 2012-2019) SSD Upgrade Bundle


DJ Fixit - Antwort

Your system came with a PCIe/NVMe blade SSD, thats on the backside of the logic board a pain to get to, its easier to add a second drive in this case a 2.5” SATA SSD like a Samsung 860 EVO. In this case you’ll use your SATA drive for your stuff and use the blade drive to be your boot drive and , apps, leaving the rest of the drive empty! So your OS has room and if your apps need scratch space they can use it as well.

Dan -

Any iMac that comes with only an SSD is, yes, a “blade SSD. Or m.2 SATA. As Dan has said, it is really hard to get to. So to replace it is a lot of work. But it is equally as hard to add a regular SATA SSD to you system unfortunately.

iMac’s come in 3 storage variants:

1. Standard HDD

2. Hybrid Drive = A big HDD + a small SSD

3. SSD

Option 1 and 2 have a SATA cable that comes from the back of the logic board and the HDD plugs into that. In this guide that is what I am replacing. Option 3 does not include the SATA cable since it would just be floating in the case attached to nothing.

The SSD and the SATA cable attach to relatively the same spot, meaning the are both super hard to get to, relative to this guide. Plus from what I understand it’s not just an “off the shelf” SATA cable.

So in your case, you could either try and replace the built in SSD or just get an external SSD, like a Samsung T5. Because getting that cable or trying to replace that built in SSD will be a huge task.

Justin Winchester - Antwort

I find I can plug the cable in without pulling the logic board fully out, knowing where the socket is and its alignment I can get the cable inserted. Granted, I’ve done it a few times.

Dan -

I have a late 2015 27” iMac with a 2tb Fusion drive on Catalina. Fusion drive went out and the actual on-board SSD part of the board is the one that’s showing the errors not the 2TB HDD drive. Took it to a technician to replace the Fusion drive with a 2TB SSD, cost me $500+ tax, has been there now for two weeks and he cannot load Catalina on it again or my Time Machine back-ups. He never removed the SSD part of the Fusion drive, which the disk utility said was bad and I’m thinking it’s still trying to boot from it. It just keeps looping. I’m telling him he needs to open it up again and physically remove the Fusion SSD also and that might let the new 2 TB SSD be the boot drive. Is that necessary if that’s what bad?

Enrique Suarez - Antwort

As long as you have a time machine backup copy, you should be good, first off.

Second, I have no idea what or how this guys is trying to install Catalina, but if he removed the HDD and installed an SSD in it’s place, then you need to have a thermal sensor to go with it, as I point out in my guide. At that point he needs to run disk utility and completely erase both the 128GB SSD and the 2TB SSD. I agree that he should have removed the 128GB SSD, but again, as pointed out in my guide, it is SUPER hard and way more labor intensive to get to.

Technically, the 128GB SSD, bad or not, shouldn’t not effect the booting of the machine. What he should do is run macOS Internet Recovery (Command+Option+R at boot), then run disk utility. Now if the 128GB SSD is dead and bad then you won’t be able to do anything with it Disk Utility, it will just give you errors. So then you just move on and format the new drive to a single partition under APFS. After that let Internet Recovery install Catalina on the new 2TB SSD.

Justin Winchester -

I don’t know why that wouldn’t work. I’d have to know more details about what he is doing or tried to get this to work. Let me know if you need more help.

Justin Winchester -

Well installed the 2 TB SSD and buttoned it up and the machine is not sensing the drive. I was 100% sure all of the connections were tight. Now I have to open it up again!!!

Norm - Antwort

It might just need to be formatted. Start in recovery mode and check for it it Disk Utilities. Make sure to expand the view the see all volumes.

Justin Winchester -

@jayman16 I successfully completed your guide a couple of weeks ago and I’m super happy with the results. Thank you! I read that you have installed windows on the 128Gb PCIe using bootcamp. I just tried launching bootcamp and immediately get an error. After some searching it seems to be related to the fact that there are 2 internal drives and boot camp doesn’t work. How on earth did you manage to install windows?

Tiago - Antwort

Both macOS and Windows need to be on the same drive which is your boot drive (the faster blade SSD).

Dan -

First, macOS and Windows DO NOT need to be on the same drive. That has never been true. And Boot Camp will work with as many internal drives as you have. If you have a Mac Pro with 8 internal drives, you can still use Boot Camp just find.

Now with all that being said, Boot Camp can be really finicky and just give your random errors or not even start. Just make sure that your Windows drive is formatted to Master Boot Record. If you still get errors, try reinstalling macOS via the recovery tool. This won’t remove any of your data, it just reinstalls the macOS system files.

Justin Winchester -

Using BootCamp it is! We setup over 200 systems at that time just not possible.

The only way is if you setup discreet boot drives one with Windows and one with macOS. If you did that way you can’t easily share between the discreet workspaces and you need to reboot each time to switch the workspaces.

Dan -

Dan We are specifically talking about my guide. And my guide is about separating the built-in Fusion Drive and then having two separate SSD’s in the iMac.

If you have a stock iMac with a Fusion Drive then it is hard, or maybe impossible, to separate the SSD from the HDD. Since Fusion is all done in software by macOS.

Once you kill the Fusion Drive and have two SSD’s then there is no issue targeting either drive for OS install, Mac or Windows. And as it was in the past, you can always partition a drive and install two different OS’s on a single drive.

Justin Winchester -

@jayman16 -I managed to find this YouTube vid which explains how to do it How to install Windows 10 "Boot Camp" on a Mac External Drive the EASY way! (2020 edition) As you can see its a bit more involved as you need a VM to work from.

What you where likely doing was a dual boot config Vs running a VM for Windows. Catalina (APFS volumes) makes isolated partitions on the same drive messy!

Dan -

I’m not sure what you are talking about Dan… First this guide was created in 2016 well before APFS and Catalina. And I only used a Windows 10 USB created from an official ISO from the Windows website and creation tool. Then I used the Boot Camp Assistant app to install it on the 128GB SSD. I never used a VM or any VM software.

Justin Winchester -

@jayman16 - I fully understand! That was part of the issue, things change! I doubt the person is using El Capitan/Sierra with Windows.

Dan -

I’m on Catalina. MacOS is installed in the 2TB SATA SSD. I just formated the 128Gb PCIe SSD with MBR and FAT and Boot Camp Assistant still throws an internal error has occurred after launching. I will try reinstalling macOS via the recovery tool like you suggested and see if it fixes anything

Tiago -

Reinstalling macOS via the recovery tool didn’t change anything. Maybe something new with Catalina? I think I’ll try fusing the 2 SSDs and give it another try

Tiago -

Great guide and thanks for taking time to do it. Peace of cake to open my iMac 27” late ‘15 and install the EVO SSD. But just like @tbilou , I get the bootcamp error “Internal Error” when trying to make bootcamp partition and install Windows. I’ve looked around and it seems like there’s quite a few people having this issue. Any advice to solve it would be greatly appreciated!

Sebastian Holmbäck - Antwort

The issue always seems to be with the boot camp installer, for me anyway. I have personally fought with it many times, and at one point didn’t even have Windows installed for about a year because I couldn’t get it working. I couldn’t even get the app to open sometimes.

Sorry I don’t have better information, but I get the frustration.

Justin Winchester -

I found the solution - pretty simple, but requires a re-install of the OS; https://blog.adriel.co.nz/2019/01/06/ins...

Sebastian Holmbäck - Antwort

Ooops - sorry. Wrong link. This is the solution to fix the issue with the fusiondrive (which seems to be the root of the problem with bootcamp); https://support.apple.com/en-us/HT207584

Sebastian Holmbäck - Antwort

Yeah, but I don’t want it to be a Fusion Drive. I wanted two separate drives. One for macOS and one for Windows.

Boot Camp working fine with two SSD’s in my iMac.

Justin Winchester -

Buenas tardes.

Es posible dejar habilitado también el disco HDD, junto con el Nuevo SSD ?


Flavio Vergara - Antwort

* Traducido a través del Traductor de Google *

Sin embargo, es extremadamente difícil. Esta guía trata específicamente sobre cómo agregar la SSD y no conservar ambas unidades. Tendría que sacar toda la placa lógica para agregar un segundo cable para SSD o HDD.

Justin Winchester -

Translation: However, it is extremely difficult. This guide is specifically about adding the SSD and not keeping both drives. You would have to take out the entire logic board to add a second cable for SSD or HDD.

Dan -

This guide is just swapping out the connection from the current 3.5” SATA HDD which is left mounted and then placing a 2.5” SATA SSD beside it. One can also take the 3.5” drive out and then use a 3.5” to 2.5” adapter frame to hold the 2.5” SSD. This setup does not give you the still faster PCIe/NVMe blade drive which is mounted on the other side of the logic board.

You are not able to use both SATA drives concurrently as this system only offers a single SATA port.

Spanish: Esta guía simplemente cambia la conexión del disco duro SATA de 3,5 ”actual que se deja montado y luego coloca un SSD SATA de 2,5” al lado. También se puede sacar la unidad de 3,5 "y luego usar un marco adaptador de 3,5" a 2,5 "para sostener el SSD de 2,5". Esta configuración no le brinda la unidad blade PCIe / NVMe aún más rápida que está montada en el otro lado de la placa lógica.

No puede utilizar ambas unidades SATA al mismo tiempo, ya que este sistema solo ofrece un único puerto SATA.

Dan -

Thanks for the guide, it looks super simple. I have late 2015 1tb fusion drive with 24gb ssd.

im just not sure what to do after new 1tb SSD instalation. Its OK just to run new system instalation via internet recovery? i remember there is a tricky part with formating a disk. In Big Sur there are kinda 2 partitions ( one read-only).

So whats the next steps after hardware instalation? is there some Instalation guide? i dont mind to erase my data and have fresh instalation.

Thank for reply in advance

Ondrej Drab - Antwort

Yes the SSD option is still great in 2021. And yes just run internet recovery, format for APFS, and install Big Sur. There’s really no issue if you’re doing a clean install.

Doing the PCIe install is a MUCH harder and longer procedure. I would not recommend it.

Justin Winchester -

and one more question. Is this SSD upgrade method still optimal in 2021? or is something better appears by the time? i dont mind to dissasemble internals, or i have friend who have skills and tools for that.

Ondrej Drab - Antwort

If you want performance the better direction is to install a PCIe blade SSD (OWC) or replace if small iMac Intel 27" Retina 5K Display Blade SSD ersetzen.

Dan -

Hi Justin! I recently bought a brand new Imac late 2015, fusion drive (1tb) , and I’m not totally happy with its speed. After doing a lot of research I found your guide, and it’s the only one I’m willing to follow, for its simplicity and straightforwardness.

In Blackmagic I get 350 mb/s Write, and 800 mb/s Read. How much would I improve those speeds with an SSD? Do you have any idea? I want to make sure the risk is worth the improvement. In any case, thank you very much for this tutorial, and your time.


Diego - Antwort

So it all depends on the drive you install. I typically use Samsung 860 Evo for my installs, and that’s what is in my iMac. You speed tests are going to be off with a Fusion Drive, since you have both an SSD and HDD. Those numbers you are getting are based off your SSD, but your real world usage will vary. Since a speed test, like Black Magic, can target the SSD or macOS partition, the speed test will look better than it really is. With a Fusion Drive macOS is on the SSD but all your apps and data are on the HDD, for the most part. Apple does move things around a bit, but more or less that’s how it works.

That being said my benchmarks are about 500 write and 1500 read. Either way, I’m very confident that you will see a huge performance boost in app launch and data transfer by swapping out the HDD and replacing it with the SDD.

Personally I would buy an 860 Evo, don’t waste your money on a pro.


Justin Winchester -

Are you able to swap out the HDD for the SSD using this method? - I can’t tell from the pictures if there is enough access there or not?..

paul.lynch1 - Antwort

This technique offers an easier way to switch out the drive. Here we’re just moving the cables from the HDD to the SSD. Sitting the drive on the edge of the HDD, there is just enough space to do this.

The other guide iMac Intel 27" Retina 5K Display Festplatte Austausch also works! But you’ll need a 2.5” to 3.5” adapter frame.

If you want to still have access to your stuff on the HDD installing it into a external case.

And lastly, if you want to keep it internally you’ll need to use a PCIe/NVMe blade SSD following this guide iMac Intel 27" Retina 5K Display Blade SSD ersetzen. This is a fair amount of additional work, but it does offer much more performance gain!

Dan -

I have successfully replaced the internal 3TB Seagate HDD with a 4TB Samsung 860 Pro using a 3D printed 2,5” to 3,5” adapter. No additional thermal sensor is required, the fans are working as they should do. Quiet in idle and noisy at load. Tested with two iMac 27” late 2015 version 17,1. Also the Fusion Drive PCIe SSD is now available as a separate and fully functional additional drive with 669 mb/s write / 1710 mb/s read.

Bayer Design - Antwort

I have replaced the 3TB stock with a 4TB Samsung 870 EVO in a 2013 27” with the latest OS. I am not convinced the thermal sensor is needed. I installed an app to read the internals. Without the sensor the SSD temp updated and fan operated normal (1100-1200 rpm). MacOS reports the SMART status is enabled. Temps for thé SSD range from 90-115 with average of 110. I ran a black magic benchmark and fan was still normal/silent. I re-installed the sensor and no change in temp reading. Exporting video was CPU intensive and the fan noise increased normal. I re-opened to glue the screen and saw the thermal sensor fell off. I’m going to remove it as this is an extraneous non-OEM part. The sensor may be designed for direct SATA drive replacements or SSDs without SMART or maybe older operating systems that don’t read from SMART. There seems to be dependence on the age, model, OS, and parts being installed. The common message seems to be that the sensor is required.

Kevin Johnson - Antwort

Does the PCI SSD “bonus” apply even if I DO replace the entire drive with a new SSD? In other words, if I don’t elect to leave the old HDD drive inside and instead replace it, will the PCI SSD portion still read as another drive?

jesuitlewis - Antwort

Just adding a PCIe/NVMe blade drive in its self won’t alter anything other that give you more space like an external drive does (just inside). To make it work you need to install the OS to it as well as your apps and make it the boot drive. Then the higher speed it offers is fully used.

This guide is just a swap out of the SATA HDD to SSD so you get some improvement as SATA SSD’s can be faster (the quality and construction has a bearing on that) but your not getting the performance a PCIe/NVMe blade SSD drive can offer.

Putting in a PCIe/NVMe blade SSD is a lot more work but offers much more performance! Here’s its guide iMac Intel 27" Retina 5K Display Blade SSD Replacement

Dan -

Yes, the factory installed PCI drive is accessible at a second drive when you replace the HDD. You then can format both drives and use them as individual drives.

Justin Winchester -

True! But the size is often so small (at it was part of the Fusion Drive set) it is not worth using. It’s almost like our bodies appendix is no longer used and sometimes gets in the way.

Dan -

It was great for me. Mine was 128GB which was perfect to use for Boot Camp Windows install.

Justin Winchester -

Has anyone had any luck finding the SSD blade for the late 2015 27’’ iMac (17,1)? OWC and iFixit sell some, that are listed as not compatible with the 17,1.

I ended up ordering the iFixit kit to replace the HDD with a SSD (waiting for it to arrive now), but will take the easy way and just install the SSD and leave the 2TB HDD. But what I really wanted was to replace my defective 128GB SSD blade with a brand new 1TB blade….much more work, but that would have been the Cadillac of solutions…

Pascal Brunet - Antwort

Went through this whole process, got the ssd installed, OSX Monterey installed….but the funnies thing: Whenever I reboot my Mac, the first time around it stays stuck at the Apple logo with the progress bar about 1/3 of the way…if I turn it off, then immediately back on, it reboots super fast and works perfectly until the next reboot. This happens every single time I boot it…very weird.

Pascal Brunet - Antwort

Reset your startup drive setting in Preferences to the new drive

Dan -

Thanks Dan - I just checked and only my new SSD shows up there as the startup drive. I selected it again, we’ll see if that does anything.

Pascal Brunet - Antwort

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