I just saw this article about putting Debian on a Mac mini via Slashdot and I bopped over to check it out. Not because I want to put deb on my Mac, but because these sorts of articles are usually educational in other ways and this was no exception. But there's one quote which is dead wrong:
The Mac Mini has a fanless external 85W switch-mode power supply, about half the size of the Mac itself (picture here), moving a major source of heat out of the metal chassis. Combined with the G4 processor's relatively low clock speed, this was presumably key to Apple's thermal design. Having less heat to dissipate means that, while the Mac Mini does have a small cooling fan, it rarely spins up to a high speed. Performing normal office work it is inaudible. The only noise coming out of the Mac Mini is the quiet hum of the hard disk, and even that can spin down automatically when the system is completely idle.
Emphasis mine. Want to hear your Mac mini rev up to Jet Engine decibels? Simply browse any website with a Flash animation, or even move around Google's new DHTML map service, or, most annoyingly, play World of Warcraft. There's reasons there are that many air-holes on the back of the box. Are you reading this on a Mac mini and want to test it? Here's a great page to try, KDDI's phone catalog. Within seconds of bringing that page up in Safari or Firefox on my mini, the fan starts revving up to full speed. As soon as I close it, the fan slows down. This wouldn't be a big deal if the fan was a bit more quiet, but it's not. It's a full-on blast which at night sounds like you have a an electric heater turned on. And I thought my Toshiba laptop got loud sometimes, I had no idea.
It seems a bit extreme - just putting even a little stress on the mini revs up the fan. It doesn't seem to be for heat, but for processing speed. The more processing power needed (like for interpreted languages), the more the fan revs. My notebook just turns on long enough to cool the system down and then shuts off. The mini, however, turns the fan on whenever it *thinks* it might get hot, and that's annoying. The direct response to certain events (as opposed to being random) makes me actually avoid certain activities. And when I'm opening tabs in the background from my aggregator, sometimes I can tell when I've hit a page with a Flash ad because the mini starts up. I'll actually stop what I'm doing to find that page and close it quickly, it's that annoying.
Anyways, if anyone has a hack where I can control the fan a bit more, I'd love to hear about it, because its bothersome when I'm playing WoW and the fan's going full-blast the entire time for very little reason - the same game on my Toshiba doesn't rev that engine nearly as much.