I'm trying to figure out what actually voids my warranty on ASUS 4850. I've gone to the Asus website (terrible) and found the grounds for "no-repair". The information included with my video card is out of date (claims that I only have one DVI port) and I can't really find more info. I've tried searching the forum but can't find a search that returns specific Asus information. But the basic question is does removing the heatsink / fan void my warranty, especially since I've read that these cards can have problems.
I'd wager that removing the heatsink does void the warranty (but I am going to do it to my Asus 4850 next week anyway!) So, if it is working fine now, don't do it. But if yours is like mine, where the temp is now climbing up near 100C at times, go ahead and replace it (I got the Akasa dual sot cooler to replace my single slot one). And plus, these days 4850's are pretty cheap, so if it gets fried and they won't replace it, it isn't too big a loss.