Overclockers Online has posted their review of AMD's fastest processor currently available: the 1.4GHz Athlon. Heres a Snip:
"If we look at the 1.4GHz counterpart, we are reading a maximum heat output of 72W! Is this a bad thing? Yes! ... Heat is something we don't want to see near a computer, as it reduces lifetime of a component. There is a rule that says the lifetime doubles every time the temperature drops 10 degrees celcius. The days that we ran our CPUs without fans or with those tiny heatsinks are definitely over!! To get rid of 72W of CPU power, good cooling is needed, and even with a high end heatsink, temperatures of 50 degrees Celsius are no exception at full load."