My recollection is that if you try to use one of these chips with no fan, the chip will just “de-clock” itself and avoid taking any damage.
I just had a guy at work claim he burnt out one of these chips by running it sans heat sink and sans fan, and destroyed the CPU.
Is that a credible scenario?
Yes, if the CPU voltage regulator does not shut down in time or the thermal monitoring is not working, then the CPU will really burn. I recall a video quite a few years ago of a Pentium bursting into flame.
CPU throttling (PROCHOT#) can not keep a desktop Pentium 4 cool enough to avoid thermal failure, if the voltage regulator does not turn off. Some mobile CPU’s may be able to work for longer, and the new ATOM CPU (single core) can run comfortably without a heatsink.