It could be windows being stupid too, permanently reducing itself to only use PIO mode (CPU INTENSIVE) for disk access after some several CRC failures in reading files. You'll probably have to force Ultra DMA on your drives.
I've had this happen on a FX5200 ages back (2004) and the card is very cool (no, the card sucks in fact, but the temperature). I don't remember exactly what causes it but forcing Vsync on absolutely everything did cause issues and cause the card to freak out (for me at least. I know the desktop...