GTX 460 sudden increase in temp during games

So I have the Gigabyte GTX 460 1 gig. and I've been having some heating issues with it. On desktop while doing some browsing my GPU temps will be at like 34C but when I alt-tab back into Shogun 2 the temps will shoot up to 57C. I think this is actually a normal temperature under heavy loads but the problem is that it's causing visual problems with the game. Like tearing and artifacts stuff like that. I've recently gooped up my GPU's processor with thermal paste but that hasn't seemed to curb any of the issues. Also Bad Company 2 is the worst. After like 10 minutes of playing the game locks up and the sound goes in a short loop of what was happening at the time of the freeze forcing a restart. After ordering case fans pointed onto the card and regooping it with thermal paste I'm running out of ideas short of just replacing the card. Anybody have ideas?