I've got one of these cards, and wish i hadn't.
I'm sending it back this week for a replacement.
Originally the main problem i had was artifacts then screen freezes and hangs, and i have to reset the pc.
Thought it was maybe the driver, but not found one that works any better. Even wiped the pc and went back to XP from Vista, but no difference.
I managed to play 5 mins of the Crysis Demo, before the usual crash, but this was only after installing Rivatuner to ensure the gpu fan was at least 60%, but it seem to crash as soon as the temp gets to about 67, I thought the card could take higher temps.
Used a couple of testing apps like rthdribl, which also send the temp up and after a few mins, causes the screen to get spots and blur and then crash.
I've got everything at factory defaults for now, might try to underclock the card see if that helps.
Not sure what else to check now...