I just got a my new iMac about a week ago, and I am already starting to get some weird graphics issues. After my iMac has been on for quite a while(10+ hours) the graphics seem to start degrading and turn into these weird rainbow pixel things. Im guessing it could be the graphics card overheating, but I'm not really sure. After I reboot, everything seems to be fine. You can check out the pictures to see what I'm saying. Any help would be greatly appreciated. Thanks 
NOTE:I have 2GB Graphics RAM, Running Lion, and my computer was running at around 160F at the time of the photos.
NOTE:I have 2GB Graphics RAM, Running Lion, and my computer was running at around 160F at the time of the photos.