The Heat Can Cause Intel's P4 To Throttle And Damage Over Time.

It may be hard to believe, but yes, Intel's high-end Pentium 4 processor, the 3.6 GHz 560, runs extremely close to its thermal limits, possibly causing the processor to throttle under a high load. That is still the case even
today, after this product has been around for several months. Even still, Intel is going to release its faster and probably hotter 3.8 GHz Pentium 4 Processor 570 next Monday.

Everything began with Pentium 4 560 benchmark results that kept becoming slower and slower with every repetition. We suspected the engineering sample to be fishy and contacted Intel.

read the full story at Tom's hardware