IMac – wrong with the iMac? (video corruption, unstable)

crashhangimacmacos

I have a 24" Early 2009 iMac.

During "intensive" use (such as Photoshop, WebGL, etc.), the system starts to become very unstable, resulting in bizarre graphics corruption and other weird behaviour. Ultimately, the machine freezes or crashes.

Somehow I managed to take a screenshot just before it went down, and I was surprised that it captured the carnage. I've censored (blurred out) some names to protect the innocent, but all the other glitches are part of the corruption.

I ran a temperature monitor in the background during use, and although it increased (as expected), it didn't seem to show unusually high readings for any components.

Anyone have any idea what could be wrong? Should I try reinstalling OS X from scratch, or is this definitely a hardware issue?

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Setup:

  • 2.93 Ghz Intel Core 2 Duo
  • 4GB RAM
  • GeForce GT 120 256 MB
  • OS X 10.8 (upgraded from Leopard, then Snow Leopard)

EDIT:

Having said that the components' temperatures seemed well behaved, I have started to notice that the problem occurs more readily when my room is warmer. Wondering if it is a heat-related problem…

EDIT 2:

Reinstalled OS X from scratch, but problem persists. I think this indicates a hardware problem. Sadface. Will open it carefully, hoping I'll find a busted fan or something silly like that. Otherwise, will take it to the shop – not keen to mess about with hardware even though it's out of warranty as the machine is still worth a fair bit I'd say.

Best Answer

It's quite likely that this issue is caused by hardware (a failing GPU, most likely) but there's a possibility that it's caused by software.

To figure out where the problem lies, boot your computer into a clean install (either Mac OSX/Linux/Windows on a bootable drive, or use your "install Mac OS" install disk/partition). If you experience any kind of problems while using a clean install of any OS, you know the problem is hardware.

You should run a backup as soon as possible, then replace your GPU (Guide) (or take it for a repair). Only attempt to repair it yourself if you completely understand the instructions, if you're unsure, a self-repair may cause more damage

If there are no problems while using a clean OS, the easiest way to fix the problem would be to reinstall Mac OSX; remember to backup your files first so you don't lose anything.

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