Add lines frameratecap=60 frameratecapGlue=30 to your variables text document in the starcraft 2 folder.
Reduce all your setting to medium.
Change portraits from 3d to 2d.
I have tried all of these solutions and I am still getting excessive temps on my gpu. I have never had any temp problems on my card with any other games. I have seen numerous reports of peoples cards overheating causing a forced shutdown.
Blizzard what are you doing about this? Have you acknowledged this as a problem?
8800 gt gpu geforce
3200 clawhammer AMD processor
Plenty of fans