Hi. When I booted the iMac (late 2009 w/ 10.9.2) this came up instead of the Apple logo (I rebooted it again and it booted back normally):
Thank you in advance. Have a happy Divine Mercy Sunday Mass.
God bless. Rev. 21:4
iMac, OS X Mountain Lion (10.8.5), iMac Late 2009
Hi Alvin777,
I just came from Apple Store after getting the same yellow ring on my late 2009 iMac.
But, unlike you, after getting this problem my iMac refused to load anymore.
Disk utility showed no errors. In the end I had to change the graphic card and now it loads properly (and no more yellow rings... hopefully).
Be careful if this happens again and make sure you get daily backups.
Hi. Thanks for the reply. It's good to know it's not an isolated case.
It's most likely caused by Mavericks, a software bug though, particularly messing the OpenGL code because a few years ago, my late iMac 2009's GPU was replaced because the screen would become garbled and would crash but mine a few days, the screen would go garbled but would still function. I've had damaged GPU's before (when I used PCs) and how this new problem occurs doesn't have the same pattern (of first becoming garbled then crashing because of overheating).
I got to the conclusion that it's a software problem because you can replicate the screen being garbled and acting weird if you a graphics tester like Unigine's Heaven benchmarking tool. It become garbled when anti-aliasing + OpenGL is run (in Cinebench, Maverick's OpenGL works fine but that may be a less heavy benchmarking tool). Click to enlarge:
Also, I'm not sure where the iMac's getting the yellow circle pattern (things should be garbled and disordered) like it's getting this pattern where it gets the logo when you use Target Disk Mode then reboot. The yellow circle is too ordered for a GPU that's overheated (usually it's thermal paste and/or the fan is broken but iStat says the fan is ok coz' the temperature of the GPU is normal for GPUs)
Before after shutting it down for about 30 seconds (so that any corrupt code gets erased in memory in the GPU) it usually gets fixed after a trip to Recovery mode to fix the permissions and select the built-in drive as the Start-Up but it would usually become garbled again after a few hours or less than 3 days but I got to fix it by running graphics intensive games with anti-aliasing, heavy textures and graphics settings set to maximum as possible- it may have kinds of "reminded" Mavericks this is how OpenGL w/ anti-aliasing should work.
If you paid to have your GPU replaced, you may show Apple that it's a software problem (by using Unigine Heaven benchmarking tool with anti-aliasing ON: http://unigine.com/products/heaven/
they could issue a kind of refund or a kind of credit, God willing.
God bless.
Hi!
I thought it was a software problem too.
In fact, mine crashed the day after installing the update 2014-002 1.0 (I had Mountain Lion at that moment).
Thing is, I was unable to load into recovery mode at all, so I couldn't get back to a previous version (without the security update). In the end I managed to get into safeboot... but time machine wouldn't load anyway.
Running disk utility was no use, no errors found, no broken permissions, nothing to check.
In one of those attempts to get into recovery, the first yellow ring appeared. I think it was, indeed, an overheated GPU after so many trials. After reboot into safeboot, the menu and background showed weird colours and broken lines like in your picture (in smaller parts, thought).
I decided then to install Mavericks to see if this could made any change or override whatever the security update messed up. After installing Mavericks, the computer couldn't get past the apple logo again, but it led me into recovery mode at least.
So I turned back in time twice to different backups without the security update. It was no use, since the iMac wouldn't load in any case. Also tried to load from another disk... no luck.
I left the computer some hours to cool down and decided to erase the HD, repair permissions, verify disk and install a fresh Mavericks. No use, and the second ring appeared.
So in the end I took it to Apple Store and explained what happened and all tests I made. They ran the hardware test and everything was OK.
They thought at first that it could be some HD issue, but I showed the pic and told them my HD was running perfectly (also, it was replaced last year).
Then I loaded into safeboot and it showed the weird graphics (and was weird enough to wonder if it had something to do with the graphic card... which seems that was really causing the problem).
So, I do think it was too much coincidence that I installed the update and then the GPU crashed. Actually, there is a GPU replace program for 2011 iMacs, but it supposedly doesn't affect late 2009.
But same happened with HD last year. At first it only was for 2011 iMacs and then they had to extend it to late 2009 because most of them were having the same error.
I'll definetely write to Apple explaining the issue.
Just be careful your GPU doesn't decide to give up like mine did without previous announcement 😉
BR!
Hi. Come to think of it the GPU problem started when I upgraded to Lion. I guess your case confirms that it was a software all along that started with Lion which Mavericks code is based from (Snow Leopard was the last very stable version of OS X by far) and wished I hadn't had the iMac opened and repaired, had I known Unigine Heaven. But it's always a blessing in disguise. At least others and Apple and other iMac users know if the screen goes garbled it's probably a software and not the GPU (coz' they can test Lion and Mavericks with Unigine's Heaven benchmarking to replicate the garbling). It's good mine's not having problems anymore too..
Hi. It came back again, the yellow circle when I switch it ON for the first this morning (I'm a shut down when I sleep type of user instead of always on). It's a weird problem. When the screen starts getting garbled, artifacts showing up, it clears up when you play something like a third person shooter like RedEclipse, in maximum setting on OS X that the late 2009 iMac can be set to.
It also passed the heavy Furmark on Bootcamp (it testst OpenGL on Windows with Anti-aliasing) as well as 3D Mark Vantage (Direct X only with Anti-aliasing) on Bootcamp. It's a weird problem. I really think it's the OpenGL drivers and not hardware.
God bless.
What Could It Be: Yellow Circle In Gray Background When the Mac Booted
