Yes, cooling is especially important now days with these super hot video cards. I hear that the 4xxx series ATI cards are running super hot (80C+) and I know my GTX260 does (75C). As a test, you can take the side off your case and blow a box fan into it to see if that helps. If so, I'd really look at adding a case fan or two (or even switching cases to one with better air flow). It's better than cooking a video card every 6 months (a friend of mine went through two of them before finally upgrading his case). By the way, once you start to see artifacts, it just gets worse over time...