Sounds like vram issue. Use catalyst control center to underdrive you ram by say 50Mhz and run the game that artifacts the worst to see if that's the issue. BTW be sure to clock both cards the same using select GPU drop down menu.
Have you tried setting your fans to 100%? 70 at idle is odd. My cards idle at 40c and I get up too 65c during BF3.
Friend i've had XFX5970 for 3 years and then it started to malfunction like leaking textures , i'm afraid same scenario as in your case i can play a game after a while a texture leak happens across the image for example some pistol leaks across the image you can still play the game but it's very anoying and it randomly happened not in all games but yes one of the GPU'S is dying you should get a replacement i got gtx580 can't say i'm sorry in any case but i'll put my money that it's dying i've had same problem's no its not PSU not it's not CPU / Mobo or drivers its GPU Itself.. hope you fix it
I have the same issue, and I'm pretty sure it's some sort of driver or card bios issue. It's not temperature and I dust periodically. My system passes memcheck and prime95 with flying colors. My 5970 passes furmark with no issues, all the way up to 99% GPU and temps way higher than my games ever see. And all this at stock speeds. But with most games, and afterwords with windows itself, I get artifact pixels and lines everywhere, pixelated textures or flashing problems in games, and sporadic display driver crashes. I've been seeing this for a long time, from at least catalyst 12.11 - 13.4. When I get some time, I think I'll try putting older ones on....I know it wasn't happening when I first built the rig.
I was a proud HD5970 owner since it came out until June, 12th and i used latest Catalyst drivers available so, I can tell you with high degree of certainty the drivers are OK. If you run the card at stock, maybe you need to sweep clean the drivers before installing the latest ones. I don't know if is a BIOS issue. If it was, I don't think the card would stand in Furmark like you said it does. It's an odd issue alright but, I would start from cleaning up the drivers. There are several tools that can do it for you. Driver Sweeper is one of them.
