This is on win7?
Try a newer driver version like 314.22
but first open "dxdiag" and see if both directdraw and direct3d are enabled.
you can type dxdiag in run or just search for it in the start menu.
I updated like 10 minutes ago, actually. I just checked, and yeah, they're both enabled.
Well there's your problem haha
80-90C is pretty hot and there is every chance it is downclocking. You should run some monitoring software and have a look at what the clock speeds, utilization and temps do while you game,
I agree with stoner here, 80-90c is quite hot and while it is entirely possible for them to run normally at that temp, it is also possible that it is throttling to save itself from damage.
I had a similiar problem way back when I had an 8800gt (single slot cooling solution from galaxy or something), it was hitting 80c in WoW then downclocked to 400Mhz before finally kicking the fan to 100% and getting back to 600Mhz in a few minutes - It was crippling lag while this process was going in.
I attributed my problem to poor software/drivers and I haven't had any problems with any of the gfx cards I've had since. (Currently using 2 gtx 580's that sit at a nice and cool 40c under load with the w/c loop)