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DevsRocks Author

Level 1

8 points

Imac display issues following Yosemite upgrade

Since upgrade to Yosemite my iMac has a very 'glitchy' display... Pixels flashing all over the screen, strange pixels following the mouse etc..

When I boot into safe mode the issue is gone so I assume that it rules out a graphics card issue. I've had a read over other posts and someone suggested to run a script to determine what is causing the error. I've done this but do know know how to decipher the output.

Link to older post with same issue and suggested script etc: https://discussions.apple.com/thread/6604981?answerId=30603036022#30603036022

I've ran the script that Linc so kindly posted above and will post the results below:

http://www.pastebin.com/embed_iframe/R5ATQcz1

I wondered if anyone can see what this issue is and suggest how I can get back up and running again.

Any help would be great.

Many thanks,

Devs.

Mac Pro, Mac OS X (10.6.8)

Posted on Sep 5, 2016 12:14 PM

18 replies

DevsRocks Author

Level 1

8 points

Sep 10, 2016 3:37 AM in response to John Galt

Hi John, is there a way that I can find out for sure what part of the hardware needs to be replaced before I purchase it? Is it the graphics card? Is it normal for the screen to appear fine whilst in safe mode when the card is failing? Thanks again, Devs.

Eric Root

Level 10

684,603 points

Sep 10, 2016 8:36 AM in response to DevsRocks

If you live near an Apple Store, make a Genius Bar appointment to have the computer tested. Supposedly there is no charge for testing. Use 2nd link if not near an Apple Store or aren’t in the US. Hardware Repair - Keeping Confidential Data Safe

Genius Bar Reservation US

Authorized Service Provider

John Galt

Level 10

146,402 points

Sep 11, 2016 9:11 PM in response to DevsRocks

Is it normal for the screen to appear fine whilst in safe mode when the card is failing?

That is possible, since hardware graphics acceleration is disabled in "Safe Mode": Limited graphics performance in OS X recovery or safe mode - Apple Support.

On that model iMac the GPU is soldered directly to the logic board, so it's not replaceable as a separate unit. If you wanted to replace the logic board though, here is a thorough description:

https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2546+Logic+Board+Replacement /15777

I'd recommend having Apple evaluate it. Some models suffered from premature GPU failures that were addressed in a recall program, but I am reasonably certain your iMac is not one of the affected models. Apple can provide a definitive answer and thoroughly diagnose the hardware so you can rule it out as a cause.

Imac display issues following Yosemite upgrade