On Dec 12, 2004, at 7:50 PM, Michael wrote:

> In my iBook it's apparently controlled by an ADT7467 which also 
> monitors temperatures, core voltage and so on. It has a few registers 
> to control at which temperature it should turn the fan on or off, so 
> it even works without MacOS :)

On my Pismo (from 2000) they designed it so that the fan would only 
turn on in emergencies, or when the temperature got too high.  I've 
only had it start on a very few occasions (such as when building KDE 
and resting on a blanket with poor ventilation).  But the fan *does* 
turn on when running NetBSD 2.0_RC4 if the temperature gets too high.

   -- MW