I have an EVGA GTS250 512mb graphics card and while playing some games my video freezes and the image that is displayed on the screen becomes pixelated with mulitple random colors. My system is completely locked up. The issue occurs at random intervals, sometimes after 5 minutes of gaming and sometimes after 3 hours. My issue doesnt seem to be caused by heating/cooling problems, I have been monitoring my system using CPUID during the crashes and all temperatures are within norms. I also recently upgraded from xp to windows 7 and have had the same issues under both operating systems. I have tried multiple drivers for the card as well.
My first suspect is always the powersupply.
Even though you pay big $$ doesn't mean they're always built top dawg,
Thermatake is good, I've got a new Black Widow 550 and it's great, nonetheless if it ever starts making weird noises or things just seem totally out of whack I'll end up replacing it.
And you should normally have a 30 day return policy if it doesn't solve the issue.
Could be a failing GPU, but I would check to see if it's the PSU first. You can get an Ultra PSU cheap at CompUSA. The Ultra PSUs are o.k, and are miles better than the power up and diablo PSUs they sell dirt cheap. You may want to test the video card in a friends system to see if it gives you the same issues as well.