On Sat, 2002-12-28 at 18:10, Nirmal Govind wrote: > Hi... I have an ibook3 (w/ benh kernel) and the fan in this machine > seems to run quite often and with a pretty loud noise.. and it turns on > even if the machine is idle and if it's not doing any heavy work.. is > there any way to control the behavior of the fan and is this advisable? > I've noticed that when it runs OS X the fan doesn't turn on this > quick...
Radeon's chips tend to turn quite hot in X with accel, at least more than in MacOS, possibly because we don't enable some power management features of those chips due to lack of docs. (Typically they can do things like suspend clocks during blanking etc...) Also, MacOS X can do more agressive power management (shutting down caches, etc...). Finally, on the iBook's with a 750FX CPU, you can switch it to low speed (400Mhz). On those machines (unlike G4 based tipb's), the switch is very fast (a few clock cycles) and so it would be possible to switch often on-the-fly based on CPU load. (though the kernel already switch it to 400Mhz when completely idle). Also, when it's switched to 400Mhz, we can tweak the CPU power supply to a lower voltage. OS X does that, I haven't implemented it on linux yet. Ben.
