I have Nvidia 460 gtx (Cyclone OC, 768 MB) graphic card and about 6 months ago it started to randomly crash and it kept crashing until I installed different drivers (usually downgraded back to 275.33) and it always worked just fine for 2-6 weeks and then it started again. Installing different drivers doesn't work anymore and I have to unplug and plug it again to get it working. I'm 100% sure it's not overheating.
It usually only happens when browsing the internet (I'm using Firefox with hardware acceleration disabled).
I have contacted the vendor and they won't replace it until it's completely broken.