Hello,

> > 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.

I think OF programs the chip with some safe values and MacOS modifies them, maybe they should be made accessible through sysctl so everyone can be as paranoid as (s)he wants. Under NetBSD the iBook gets pretty warm but it doesn't (really) cool down even when sitting there idle, looks like there's something else missing.

have fun
Michael