intel is really doing a great job in thermal management.
i had an experience with celeron processor (1,6ghz socket 478) running without fan for 2 weeks until i noticed there was something wrong with the temperature (looking via asus probe and the bios h/w monitoring). then i fixed the cpu fan cable which hold the fan from rotating.
it is still running fine now as one of my working place client computer without any hardware failure or so.
back at the office there was a athlon xp 2600+ that was set wrong fan rpm, and in a sudden the motherboard died, so we had to replace it with a new one. i don't know about the new k8 amd's processors management dealing with dead fan or over heating problems.