Help: My iMac (late 2013) is stuck in bootup sequence.

[hjalte]

I have an 27" iMac from 2015 (it's the late 2013 model, with nvidia graphics and an i7 CPU).

Yesterday I was watching something on YouTube and suddenly the colors turned red, green and blue like. I could still see the image, but the it looked wrong. My computer rebooted and everything was back to normal.

Then it happened again maybe an hour later. Next morning, when I turned it on, it would go to the login screen. When I logged in, it would get stuck with the progress bar half full or so.

I tried to go into recovery mode, safe start etc without any luck. Now, it gets stuck on the black screen with the apple logo, again with the progress bar about half full (like this: https://support.apple.com/en-us/HT207019).

It also lost connection with my keyboard an mouse, so I am using an old windows keyboard. The only thing I can get working, is entering the Startup Manager by holding down the alt key.

I also have windows installed via bootcmp, and when I try and enter that, it shows the blue spinning thing for about 10 secs, then reboots with a very low sounding chime.

After some reading, I suspect that it might be the GPU, but not sure.

What can I do?

 

[fastlanephil]

Did you try shutting down and restart holding the D key down to bring up Apple Diagnostics?

 

[hjalte]

Did you try shutting down and restart holding the D key down to bring up Apple Diagnostics?

Yes. It doesn't work. It goes to the same black boot screen (with the white apple logo), and the status bar stops around 50% in.

 

[Fishrrman]

I'll guess a GPU failure.

 

[TwoH]

Issue does sound very much so to be a GPU failure, not common on the slim machines - but sadly it does happen.

It is soldered to the logicboard too.

The fact it wont even boot into recovery or safe mode and it only boots half way does give more suspicion it is to do with the GPU.

 

[r6mile]

This is exactly what happened with a 2011 21.5 iMac I fixed up recently. GPU was dead and I had exactly the same symptons - thankfully I was able to replace with a Quadro K610M. Unfortunately on the 2013 you don't have that option...

 

[hjalte]

Yeah, that's what I am afraid of.

I did manage do to a hardware test today. Came back without any errors. Should it provide en error if the GPU is dead?

I'll take it to get looked at tomorrow and get an offer for the cost of the repair.