I haven't used Windows for a really long time, but a few months ago I upgraded my Linux box with an NVIDIA GTX 460 graphics card and installed Windows 7 Ultimate (64 bit), just to be able to play StarCraft II.
I finished the single-player campaign, and haven't booted into Windows ever since.
A couple days ago, I booted Win 7 again to make sure it was ready for Crysis 2, but I was greeted with screen flicker and random triangles:
Now, everything was perfectly fine a few months ago, and everything still works perfectly under Linux, including 3D graphics. 100 iterations of MemtestCL up to 900 MB (the card has 1024 MB memory) reveal no errors either.
I've also managed to install all Windows updates and the latest drivers from Nvidia, but no luck there either.
To me, this definitely looks like a hardware problem. However, everything is fine under Linux, and I'm not a Windows expert, so I thought I'd give it one last chance before taking it for a repair/replacement and ask if anyone on SU has any idea what might be causing this.
Following gordoco's answer, I checked the temperature and fan speeds, and the card is running at a cool 40-45°C, with the fan at 40%.
But things got stranger while I was running these tests. After a cold boot, I was unable to reproduce the problem. So a soft reboot from Linux to Windows reproduces the problem, but a cold boot into Windows doesn't.
One fact that might be related is that this box normally acts as a download box & server, so it runs headless and goes weeks (sometimes months) without a reboot.
Between the cold boots, the new NVIDIA drivers and Win7 SP1, the problem seems to have resolved itself and I can't reproduce it anymore, even with a soft restart followed by hours of Crysis 2.
19 years, 2 CS degrees, and I still don't "get" Windows.
Anyway, thanks a lot to those who replied.