Originally Posted by CrazeD
Turn the fan speed up. The stock cooler sucks.
doubt that's the problem if it only gets to 70c under Crysis and he's said he's turned them up to 40-50% which is what i have on my Sapphire 4870, saying that when my 4870 goes a few degrees over 70c it seems to act up, luckily with fan speed at 45% i seem to get about 55c while gaming.
I'd say MAYBE RMA it? if you've tried installing the drivers multiple times and are still having issues maybe it's just got a problem?