why are you assuming your cpu is shot? that dont even make sense.
Yeah, really. I don't know how that can even happen.
For your CPU to have any physical problem it needs to have either been dropped or had its pins touched/rubbed by a stupid builder, or in very VERY rare cases from AMD or Intel, its actually DOA.
I wonder if I can do that stress testing on my Core i7 and see how it goes.
P.S. If you have an Intel Core 2 Duo or etc. Intel dual core, most of the time the processor will underclock itself in order to save the chip itself from being fried from overheating.
If your chip is ACTUALLY overheating, then you should probably double check that there is a nice even amount of thermal paste between your CPU and heatsink, the heatsink is PROPERLY attached (LGA775/1366 stock coolers are a bitch to install), and that there is good airflow in your case.
If you have stock cooling and the above options failed I would suggest looking into aftermarket heatsinks.