iMac Mid 2011 - Red Screen

[Crash Davis]

I've never had any previous issues but a little while ago my screen turned completely red and I couldn't do anything else. So I rebooted and it showed the Apple icon boot screen but had pink candy stripes and then went to an all gray screen. It wouldn't go any further.

I tried rebooting a couple of times but it did the same thing.

I rebooted and held down apple+r which then also took me to the gray screen. So i left it and went to lunch. When I came back my screen was black. I held the power button to turn the screen off and then turned it on.

This time it booted like normal and I'm typing this on it.

So, I have no idea what is going on. I can see that there may be a known issue with the AMD Radeon 6970M used in these machines, but I don't know if it's an issue here. Any way to check for that? Should I take my machine in to have it checked out?

Thanks for any feedback.

 

[briloronmacrumo]

Yes, definitely take it in to Apple and have it checked. The genius bar folks can run diagnostics on it. My mid-2011 iMac had similar issues and both the GPU and the original 2 TB internal hard drive were failing. My GPU and HD were replaced under warranty ( no charge ) about 1.5 years ago but I don't know if Apple still honors this warranty. This GPU on this 2011 iMac had lots of failures.

 

[JoeInMilwaukee]

Do you have an Apple Hardware Test DVD that you can try booting the machine from?

 

[havokalien]

What your describing is video card failure.

 

[Hirakata]

I've never had any previous issues but a little while ago my screen turned completely red and I couldn't do anything else. So I rebooted and it showed the Apple icon boot screen but had pink candy stripes and then went to an all gray screen. It wouldn't go any further.

I tried rebooting a couple of times but it did the same thing.

I rebooted and held down apple+r which then also took me to the gray screen. So i left it and went to lunch. When I came back my screen was black. I held the power button to turn the screen off and then turned it on.

This time it booted like normal and I'm typing this on it.

So, I have no idea what is going on. I can see that there may be a known issue with the AMD Radeon 6970M used in these machines, but I don't know if it's an issue here. Any way to check for that? Should I take my machine in to have it checked out?

Thanks for any feedback.

I just went through this two weeks ago. It's a free of charge video card replacement within four years of purchase date.

https://support.apple.com/en-us/HT203787

 

[havokalien]

Regardless of the repair, I would guess maybe the Thermal paste was not put on enough or too much, and/or heat sensor got damaged/not plugged in and not enough cooling happened and the card ate itself. Ive done it before trying to reflow old video cards. Maybe the new card did not mate up to the old heat sink in the same way and something didnt get cooled. The fact is intermittent is what makes it up in the air, but the bars are a clear sign of failure, just search youtube.