It's usually recommended to keep the loads below 70C or as low as possible. Even though 70C is still safe. It's possible that the high temps are contributing but there are other factors.
When I'm playing BF3 on my two GTX 560 Ti the top card usually tops out at 75-80C, and I can play like that for hours without a problem.
When I'm playing BF3 on my two GTX 560 Ti the top card usually tops out at 75-80C, and I can play like that for hours without a problem.