I have a 6950 and use Guiminer. I was able to play bioshock infinite the other night and mine with no issues, guiminer simply autoscaled my mining back to 150 Mhash/s and the game ran smoothly. My card was around 70 degrees C though I have a custom cooler. And I've pushed this thing to 80+ degrees with no issues so I'd say there should be no issues, as long as you either manually scale your mining back or let the miner do it for you. On another note, WoW is much less graphically intensive than bioshock so I'd say you can do more than 150 while gaming, albeit it is a slower card so maybe not... Try it and find out
Just watch the temps and make sure you don't bring them too high. Your best off trying to keep it below 90C.
