Screen flickering and then shut down
Got this problem recently on my iMac 27” late 2015 model.
The iMacs screen start to flicker briefly and then the computer shuts down. Some times it can run OK for about 10 to 15 minutes, but some times it can only do for a couple of minutes.
It tries to reboot and then shuts down again but sometimes it just stay dead. I have to pull the plug from the socket and reconnect it again to get it to boot.
I have run the Apple diagnostic tool by pressing “D” during it boots up, and it returns:
No issues found
So, what could be wrong before I open the screen assembly for further check? Any thoughts or comments?
Many thanks.
Ist dies eine gute Frage?
Sadly, diagnostics won't test everything. Power supply and displays being the ones you could be facing here.
Can you give us a bit more here. Did you even have the system serviced or opened to add or replace something?
von Dan
Bought it over market place, and the previous owner did open it and have SSD upgraded. By the way, I have the screen assembly opened again, and have it connected with my Thunderbolt Display. Here is what I found so far:
1. Pictures can be displayed on external monitor correctly (thunderbolt display).
2. But the fan is too loud, I have to use the fan control software to bring it down a bit. Not sure if this is due to the display assembly has been removed and lead the iMac in "open" environment.
3. CPU has 70% occupied and most of it are from "kernel_task", not sure what it is, but looks like I can not stop it manually.
@danj
von Tom
One more thing I also found is that one of the metal plate on the right side of edge (there are two there with wires under it) are loosing and found one end was broken, not sure if this will cause the problem or not.
von Tom