Harddrive upgrade > no harddrive nor cables in my iMac?

Wow thanks so much for your help. In either case it looks like it will get a lot more complicated. If I were to get a SATA drive cable to try to install that, I assume I would need to get all the way under the Motherboard where the Blade SSD is also located? And if that Balde SSD is the one not working in the first place, do I need to remove it or can i just connect a SATA drive cable and attach the new SSD drive i bought to it?

What do you recommend? Thank you again so much!

@antoniusw - The Blade SSD is a little more cost as it's a PCIe/NVMe interface drive which does get you a lot more performance.

In any case you do need to remove it and you also need to at pull the logic board out to gain access to the SATA driver headers to install a new cable it you go that way.

I'm guessing you already ran Disk Utilities from the external drive on the internal and also looked at the hardware inspector (from within the About This Mac) to see if the drive even is seen.

Often SSD's burn out from data churn so the size and needed storage you need maybe higher than you think sticking with a single SSD drive.

While Apple pushed the Fusion Drive concept, they missed it! It's not using a caching setup but just dedicated use of the drive. So you might want to install your SATA drive in combination with the PCIe/NVMe drive. Here this drive becomes the Boot drive hosting the OS and your Apps and really nothing else with at least half or more of the space unused depending on your workpieces size.

(Cont) that is is you are doing still & video rendering, object base art, AI or sizable number crunching.