Re: G5 thermal module... Louder under Linux than OS X?

[Shyamal Prasad <shyamalprasad@verizon.net>]

    "Christian" == Christian Luijten <christian@luijten.org> writes:

    Christian> Hi, I've installed Debian on my PowerMac7,3 a few days
    Christian> ago (thanks again, Sven) and it seems that it is louder
    Christian> than it is under OS X. A quick look inside showed that
    Christian> the two front CPU fans are blowing at full power,
    Christian> whereas on OS X they would be blowing at a fraction of
    Christian> this speed.

I don't seem to see this problem (Dual 2Ghz PowerMac7,3), but I have
two other computers often running which are much noisier. You can
actually look at the details in /sys/devices/temprature/ if I remember
correctly. You should be able to track the fan speed over a period of
time. 

    Christian> Are the speeds user-adjustable or are they fiddling
    Christian> with constants in the driver or how can they be
    Christian> controlled, if at all?

I don't believe there is a way to control them. You can look in the
kernel source drivers/macintosh/therm_pm72.c file if you want details:
it looks like a PID controller algorithm with fixed constants.

    Christian> Would it be possible to turn all fans off for a few
    Christian> seconds and turn them on one by one? I have a strange
    Christian> noise coming from the case which I hope to pinpoint.

Perhaps you need to remount the pexiglass cover? That did it for me :-)

Cheers!
Shyamal