Display Issue - iMac freezes, display becomes pixelated

This past week Applecare and Apple engineers reviewed my pictures and confirmed it is a bad video card. Since the card has already been replaced Apple thinks the logic board may be causing the graphics card to fail. So the next step is to replace the logic board as well as a new video card since the newest one is already fried. Since I have applecare they are going to send an outside repair service to my apartment and replace both the logic board and video card. That should happen sometime next week. Once these parts are replaced I'll update this thread again to whether or not that fixed the issue.

I just found this video on youtube. This is EXACTLY what my imac is doing.

http://www.youtube.com/watch?v=sVHCn9VSyIA&feature=related

Another video of the same issue:

http://www.youtube.com/watch?v=yGF0Jh6vbRs&feature=watch_response

Update:

Like I mentioned before, my local Apple store performed diagnostic/hardware checks on my imac and found no problems. They could not get the computer to reproduce the issue I was seeing. So I picked the computer up and brought it home. Later that same day the computer froze.

I called the Apple care number to report my problem again and to let them know that the in-store repair did not work. My Apple care advisor and I decided to try and narrow the issue down. We created another user profile to see if this issue was specific to my profile. After 2 days of using the computer under the new profile I didn't have any issues of freezing. At this point I called Apple care again to let them know it seemed to be working. I had a different advisor this time around and he suggested we format the computer and reinstall everything. This way if the issue happened again we would know for sure it was a hardware issue.

We began the reinstallation first by inserting the Mac OS X CD that the computer came with. Before we erased everything my advisor had me run a check on the hard drive itself. To the advisors surprise the check actually came back with problems with the hard drive. The utility we used to check the hard drive also had a feature to repair these problems. It was the advisors thought that the problems we found could possibly be the cause of the computer freezing. So we let the computer repair itself and since that repair I haven't had any issue with freezing. I have been using my original user profile since the fix.

If anyone else is having this issue I would suggest trying the hard drive fix. Thanks Apple care!

Unfortunately after about a week of freeze free, it happened again today. This time the safari window "contained" the pixels and color. I uploaded new pictures to the flickr site above. I will call apple care again tomorrow. I think the next plan of attack is to wipe the drive and reinstall everything. If it continues after that, the problem is obviously a hardware problem and is something the utility for performing hardware checks doesn't look for. I am bummed as I thought we had found the issue.

So yesterday I touched based with my Applecare tech and we went through and formatted/reinstalled the OS and we're going to see if this solves the issue. I would like to note that we did use time machine to copy over user files such as music and pictures. All programs were reinstalled from scratch (just finished that today). I'll be sure to post an update after a week or so and let everyone know if this solved the issue. Fingers crossed

Hi Juonamacbookpro,

Have you had any luck with a solution?

My imac froze again today, I have uploaded more pictures onto flickr. This time I was in the middle or writing an email when it happened. Also this is after reinstalling and formatting the operating system. I will give applecare another call. Not sure what our options are now.

Also here is another video on youtube:

http://www.youtube.com/watch?v=rVQrua7Nuf8

This video is labeled as the graphics card freezing. Could that be a possibility?

I spoke to Applecare earlier today and I'm taking the computer into the apple store again tomorrow. They are suppose to replace the graphics card. I will post another update to whether or not this solves the problem.

I received my iMac back from the apple store today. They replaced the graphics card (ATI Radeon HD, 4850 512 MB). Everything seemed ok until tonight when the computer froze again. Interestingly enough iTunes kept playing, although I couldn't change the song with the keyboard. New pics are uploaded to the Flickr site:

http://www.flickr.com/photos/53063215@N04/

I'll give Applecare a call tomorrow and follow up with another update.


**Edit: The Apple store referred to the issue as "snow pixels" or "pixel snow", I forget which one. I wanted to get that into the body of a message in case someone searched for it.

Message was edited by: Billy Bogs

Update:

Apple certified technicians came to my apartment today and replaced both the graphics and logic board. Hopefully this will resolve the issue. I will update after a week or so or if the problem reappears.

So far so good, I have been using the computer on a regular basis everyday since the logic board replacement. For now it seems like the solution is to replace the logic board & video card. For those still within the timeline of returning the computer, I would just exchange for a new one. For those past that date like myself, I would try and have them replace those parts first.