There is an unstable overclock somewhere in your system. Nothing to do with the card. All GSOD and screen corruptions with the 58xx series are related to unstable overclock of RAM/CPU/GPU. It's simply more ''touchy'' then your NVidia card, and reacting badly to something unstable in your system. Just recheck all your OC settings, voltages, etc. Check your RAM for errors, Furmark, Prime for more then 8 hours...
I'm playing Stalker CoP since the first day it came out, in Tri-Crossfire (5970+5870) and didn't had a single crash, GSOD, freeze or bug.
I didn't got a single crash, freeze, bug or GSOD in the last 2 months in Tri-Crosffire, and I've played over 8 different games to the end till then (Steam holiday sale). Stalker SoC with Complete Mod, Stalker Clear Sky, Stalker CoP, Jade Empire, King Bounty Armored Princess, Universe at War, Dragon Age Origin and Mass Effect 2.
Not a single crash or freeze. 5970 OCed to 5870 level, i7 920 at 4.0. Rock stable.