I see a similar thing with BIOS 0521, I can hold PL6 on the 266 strap well over 1200mhz with earlier BIOS's but with 0521 I have to use PL7 & pull in all the phases.
My 4870X2 runs great on my DFI P35 but like you say I have only ever run XP SP2 or Vista 32Bit so it is possible you are seeing a 64 bit issue
I am using the BETA 8.9 drivers but retail 8.8 was fine.
The only way I can get my driver to stop responding if I run an unstable setup, overclock the card to far, overheat the card, or push the PCI-E frequency up too high.
CN

Bookmarks