oke guys i had the same problems ( card crashes @ random moments ), contacted EVGA but their suport realy sucks!
so did some tests on my one but no results. updated my BIOS, Vista 64 and EVGA GTX 280 FTW drivers. again no results...
then i opened my case started to pick around on the 8pinE conector cable and
BOOM black screen...
first i thought it was the cable so I replaced it with an other one, even tryed other 8pinE connections on my PSU.
but still when I picked around on the cable my card shuts off, think it's a bad manufacture problem.
hope i helped some of you guys because i was getting pretty desperate 2