Greetings,
I think the Heating has become a fear factor in Processor world. But seriously I feel that if I can keep my processor utilization to 100% and if die teperature is still around 85° (For Athlon) I have peformance I would expect.
Also heating problem not is not just with the processor if you are using some el-cheapo motherboard other components even having a so called heat resistant Intel processor would start crying. ( I tried seti benchmark on some branded Intel p4 systems and my own home AMD XP )
Typically I would benchmark with the numbers that I mentioned earlier.
Ofcouse if processor is going to the max rated temperature even if it is not been in 100% utilization then you are in trouble.
Regards