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As the neighborhood computer repair guy, my friend gave me a broken iMac and told me that if I could fix it I could keep it. The exact details are:

iMac mid-2011 27"

3.1GHz i5

1TB HDD

8GB RAM

AMD Radeon HD 6970m 2GB graphics card

It is randomly rebooting, often just seconds after power up (e.g. it can't make it to the login screen). Its as if someone completely pulled the plug on it and then the computer tries to turn back on.

When the issue first came up, he brought to to Apple and they replaced the PSU. The problem still happened. Then they replaced the logic board. No luck. They gave up at this point, and he gave it to me.

The first thing I thought, if it wasn't the PSU or logic board, is that I should try just simply swapping the RAM. No luck. Then I tried replacing the HDD with an SSD. The computer made it through the OSX install just fine, and when it boots its wicked fast. I thought I had fixed it. Then the next morning I got up, powered it up, and it very rarely makes it to the login screen - the problem was still there.

At this point, every single part in this computer has been replaced and/or tested except the graphics card (Radeon HD 6970m 2GB) and the optical drive. I am also aware of a defective line of these exact iMacs with the exact same graphics card that Apple actually issued a recall on (see here: https://support.apple.com/en-us/HT203787) Unfortunately this particular iMac was purchased more than 4 years ago so Apple won't replace it.

Is my problem most likely the video card? Am I stupid to go and spend $250 on another one off eBay, or is this computer simply cursed.

Thanks for any help. I would really like to get this working - its a very nice computer and as an amateur video editor it would be wonderful to have a decently powerful Mac (also 4K displays are nice!).

TL;DR

Got a 27" iMac free. It randomly reboots. Have tried replacing every component except graphics card. Can a graphics card cause random reboots, and is it worth replacing?

willem.hill
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1 Answers1

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You may find this question of interest to you.

Unfortunately, this iMac still has intermittent problems and sometimes boots and sometimes doesn't. When it doesn't it just keeps restarting, and even when it does boot it will randomly reboot at some point.

However, to answer your question, yes, a graphics card can cause random reboots. Whether or not it's worth $250 to replace only you can answer. Obviously, if it fixes the problem it's money well spent. If it doesn't, then not.

But it's what I wanted to do next on the iMac I was troubleshooting, but the owner decided to call it quits. If it was me, I'd personally take the plunge and if it didn't resolve the problem I'd try and resell the graphics card. But that's a personal choice on my behalf and you need to do what you're comfortable doing.

Community
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Monomeeth
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  • Just thought I should tell you what ended up happening. I popped the graphics card in the oven for 8 minutes at 400 degrees. Repasted it, reassembled it, and it hasn't crashed since. I don't know how long it will last though. – willem.hill Nov 30 '16 at 03:50
  • Thanks for sharing. How long has it been since? I might consider doing the same thing if it's been a while since you've reassembled it, especially since the user in my scenario isn't using it anymore. Nothing to lose by trying! – Monomeeth Nov 30 '16 at 03:59
  • That's exactly what I thought - the GPU is dead any way so I have nothing to lose. Its been approximately 24 hours since I reassembled it. I immediately ran a graphics stress test while checking temps and everything is fine. Also something interesting I've found out - before I did this the power supply area (top left corner) got very hot and now it is cool to the touch. – willem.hill Nov 30 '16 at 04:03
  • I've also used it daily since then (maybe 5 hours a day, giving it 10 hours of total use). It seems rock solid, but I'm still doubtful. – willem.hill Nov 30 '16 at 04:04
  • Very interesting! The iMac I was working on also got very hot during use (enough to burn you if not careful). I will speak to the owner and see if they're happy for me to do the same thing. Thanks again for sharing. :) – Monomeeth Nov 30 '16 at 04:32
  • Yeah sure! Glad to know someone else has the same problem. Let me know how it turns out. Also pulling the logic board and disassembling the heatsink assembly is a little bit of a PITA. Just FYI. – willem.hill Nov 30 '16 at 04:33
  • Not sure if you still care/this is relevant, but the iMac is still working great! Its currently driving 2 1080p displays in addition to the 1440p built-in display and it works perfectly fine. – willem.hill Feb 25 '17 at 03:30
  • Yes, thank you for the update! I really appreciate it. I actually have the iMac in my possession and plan to do the same thing in the next couple of weekends. Good to know that yours is still working well! :) – Monomeeth Feb 25 '17 at 03:46
  • Yeah its really not that bad. The worst part is taking out the logic board. Also not sure if you could answer a newer question of mine, since you're presumably more knowledgable than me: http://apple.stackexchange.com/questions/274356/can-i-have-the-itunes-index-file-in-a-different-location-than-my-media – willem.hill Feb 25 '17 at 03:50
  • @willem.hill So, I've finally got around to having some time to do this, so I'm taking the old iMac apart today.I just wanted to confirm that when you said you popped the graphics card in the oven for 8 minutes at 400 degrees you meant fahrenheit and not celsius? I can't imagine it'd be celsius (too hot) but wanted to double-check. :) – Monomeeth Apr 20 '17 at 23:25
  • @willem.hill Just letting you know I ended up taking it apart today. I did the same thing as you (placed it in the over for 8 mins and repasted it before putting it all back together). Worked like a charm. I've rebooted it over 20 times since and all seems good so far. :) – Monomeeth Apr 21 '17 at 13:19
  • Glad to hear it; its amazing something so questionable seeming is so reliable of a fix. I use mine for video production almost daily and its stable as a rock... – willem.hill Apr 22 '17 at 14:41
  • Long time, no see! anyway, it finally died... I'm currently parting it out on eBay, with little success. – willem.hill Nov 02 '17 at 03:01
  • Thanks for the update! :) So, that’s about a year extra you got out of it, right? How did it finally die? GPU? – Monomeeth Nov 02 '17 at 03:25
  • Yep, GPU died again and didn't want to bother putting that much time into it again to have it die a few months later. – willem.hill Nov 02 '17 at 03:36
  • Plus I thought that I could get a decent amount of money out of its parts... unfortunately, that seems to not be the case. It was given free to me though, so hard to complain about... – willem.hill Nov 02 '17 at 03:37
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    @willem.hill same thing happened to be, the refluxing the connection is temporary. I thing a better solution would be to give it to the proper electrician who is pro in re-sodering the components. This will give another 4 years to your GPU – gfdsal Mar 12 '20 at 21:34