The last three or four weeks, the CPU in my PC has been hitting 105 degrees (centigrade) when it is busy, which is obviously hot enough to boil water!
I was getting a little concerned, as I believe the safe limit quoted for this 3.6GHz processor is 75 degrees. As it turns out, the main problem were a few (relatively small) dust balls that had formed under the fan, above the heat sink. Having learnt that a fan spinning at 3500 revolutions per minute does not get on very well with human flesh, I eventually got around to actually turning off the PC. I removed most of the dust with a funky little USB vacuum that Losha’s family recently gave us (powered by an externally powered USB hub, so I didn’t have to worry about slicing the vacuum to pieces instead of my finger ).
Anyway, short version is that although the room temperature has also dropped by 3 or 4 degrees, to 28, that the CPU itself is now idling around 62 degrees, and no longer breaching the 80 degree mark, even under heavy load.