iMac (27in, mid 2010, i7 2.93ghz) has green and pink squares on the display

What points away from a video card issue is that the image in the center is unaffected, like it is only the desktop image is affected. Do you see the squares when in an application?

It seems to take several hours before it appears. So, when it sits for a while, they start showing up.

That could indicate a heat issue affecting the video hardware. Some things to mitigate heat are:

1) Clean the air intakes on the bottom of the computer. It's surprising how much lint can accumulate there.

2) Make sure nothing obstructs the long exhaust air slot at the top of the iMac's back panel. The back of the computer case should be 6-8 inches (150-200mm) from any object such as part of a workstation.

3) Be sure people are not stuffing books and papers between the workstation and the bottom of the computer.

4) That model iMac came with disks. Find the one that includes Apple Hardware Test and run it. If you get an error, report it to us. Error codes that include "SNS" indicate a sensor problem. Codes with "MOT" suggest a fan motor is failing or has failed

5) Review this Apple article to learn how to check if a runaway background process is using too many processor cycle and running up the temps:

http://support.apple.com/kb/TS1473

6) Get a temp monitoring utility to see how hot various components are getting. I like Temperature Monitor:

http://www.bresink.com/osx/TemperatureMonitor.html

It puts the temps in your menubar so you don't have to invoke Dashboard like some other temp monitors require. Here is what my Mid-2010 27-inch 2.93ghz quad-core i7 reports with Mail and Safari open, and about 16 tabs running in Safari:

I'm getting this same error but a lot of the time.

I used the Temp Monitor and my temps are way higher than yours...any way to isolate? I have the 27" i& mid 2010 iMac.

Any way to isolate the issue?

I'm not sure my issue is related to heat...I turned my iMac off for the night and it was happening as soon as I turned it on.

Hi,

I also see problems like this on my iMac mid 2010. The first time they showed up was after a software update about about a year ago but i never had time to investigate as it got away by itself.

About a month ago it showed up again after the latest iTunes update on Snow leopard but this time it was much worse, i got much more distortions, system hangs and kernel panics.

I tried to find a way to reproduce the problem but it seems hard. I'd get it just about everytime the system returned from sleep. The problem did not seem related to heat in my case. Checked for possible problems that was related to disk and memory with several diag tools but no luck there. As a last resort I did a clean install with Lion and installed all software updates but iTunes.

Everything worked fine until a few days ago when the distortions came back again. No kernel panics yet but anoying as ****.

Any suggestions? I guess it could be the graphics card but I did a stress test by playing a demanding 3D game in bootcamp Win7 fullscreen for about 1 hour, that should have been enough to kill the card.

I've been having the same issue here. Same exact model and has been ongoing for a few months now. It's intermittent and only happens after waking from long periods of the display being off/sleep. I leave my hard disks on (SSD primary) with only the display sleeping. The glitching is almost instantanious when my secondary display is turned on which causes the system to hang or crash with the pink and green squares (display port to DVI adapter).

I'm guessing it's not totally related to the Graphic Card since I can play 1080p HD video without any issues and run Steam. I believe it does have something to do with heat, except with cooler temperatures versus overheating since the issue goes away once the system has warmed up (for me situation). My guess is weakened solder points in the logicboard that expand when heated causing improved contact. I want to correlate the issue to Mavericks since it happened right after I upgraded, but the fact that it dissapates after usage makes it seem completely a hardware issue.

I'm sure if I bring it to apple or a service center it will cost a few hundred to fix...any suggestions or solutions are much appreciated. Dealing with it for now since it runs after warmup....sad I have to say that about a Mac.

Hi - I am dealing with this issue now and I am wondering if you ever came to any conclusions about what was malfunctioning?

Thanks!

Daniel