these quirky issues are popping up all over the place with the 5 series cards.....
many ppl find (unfortunately) reinstalling windows with the card installed is helping, if you've tried all the drivers
& the problem persists this may be worth a shot..
the H/W in general is proving to be ok...... so its just a case of finding a configuration this card likes...
i myself run a dual-boot setup with the HD5970, but only one of the Windows 7 installs will game
, the other simply gives me a BSOD whenever i run anything graphically challenging...
yet i know its not a H/W problem as the other install has STELLAR performance, others are seeing the same.
currently buying into ATI, also nets you a whole bunch of compatibility issues.... so patience is required when going ''Team Red
'' have you tried these drivers.. 8.70 RC2
also.....ppl are finding the VRAM on these cards is overheating & causing the drivers to fail..... ppl have been placing ram sinks on the backs of the cards, it seems to help (though im not saying this is the problem)