2013 iMac not able to boot to anything

infinitefire

macrumors newbie
Original poster
Mar 5, 2019
2
0
Hey everyone,

I've got a client's iMac that I can't seen to diagnose the issue although I've tried everything.

The iMac is a 2013 model - not too sure of the specs but with a mechanical HDD.

The client reported (and I've confirmed) that the iMac takes a very long time to start up and when it does eventually start up it freezes and powers off.

It didn't always boot up completely. It would boot probably 1 in 10 tries and then the other 9 would crash/freeze at various points along the loading bar.

I initially though it may be the hard drive but it does the same when you try to use local or remote recovery (cmd r or cmd shift r on start up) or trying to boot to an OS I've installed on an external drive, using option. During both methods it eventually crashes after a number of seconds - sometimes a minute or sometimes 15 seconds or less.

I've reset PRAM, VRAM and SMC. I've tried to boot in safe mode but the same outcome. I've performed the diagnostic test which comes back without any errors. During the test the fans spin up which makes me think it's not a heat and a T junction issue (although I can't feel much air as it's trying to boot but don't know if that's normal).

I've open it up and replaced the HDD with an SSD and replaced the ram but this issue remains.

My final guess is logic board or more specifically the GPU failing.

I'm guessing it's now a Norwegian Blue but wondering if any of you had any final ideas.

Thanks in advanced.
 

infinitefire

macrumors newbie
Original poster
Mar 5, 2019
2
0
Did you check the PSU? That would me my best guess.
Yeah it could be that but it’s random when it eventually shuts down so unless the power draw changes on each boot?

How would you recommend testing it? It visually looked ok and the hardware test didn’t show anything (i dont know if it tests PSU).
 

MandiMac

macrumors 6502a
Feb 25, 2012
664
306
Yeah it could be that but it’s random when it eventually shuts down so unless the power draw changes on each boot?

How would you recommend testing it? It visually looked ok and the hardware test didn’t show anything (i dont know if it tests PSU).
Well, the power draw is actually constantly changing, and if you say that the crashes/shutdowns occur always in the same ballpark (+ or - a few seconds), it could be the PSU.

For testing, I'd recommend that YouTube is your best friend here. I never had the situation of having to check a PSU myself, but there's some folks out there who already did :) I hope you find a nice how-to video!