iMac G5 "windfarm"
Hi,
it is my first time I run linux on an iMac G5 and have some doubts about
its cooling.
I noticed that while installing Debian, the fan spins at full speed and
it really deserves the term "windfarm", it is as loud as a vacuum cleaner.
Once Linux is fully installed, the system runs quiet when doing nothing
(console prompt) and remains quiet when doing several things (also
unexpected ones).
However, e.g. opening GIMP, the fans whir up, just to slow down
immediately. Then, running a filter is smooth (a bit unexpected).
What I find strange is that fans run shortly full-speed, then stop after
a second.... or sometimes two!
I have never run MacOS on this system so I can't tell if this is normal
and if the fan has any intermediate speeds, but this behavior seems strange.
1) if the CPU is under "slight load" I would expect the fans to
stabilize to a low speed to keep it cool
2) if the CPU has high load indeed, then it probably takes more than
just 1-2 seconds to clear it!
in dmesg I see:
[54879.528590] windfarm: Overtemp condition cleared !
[55034.523862] windfarm: Clamping CPU frequency to minimum !
[55034.570358] windfarm: Overtemp condition detected !
[55036.462349] windfarm: CPU frequency unclamped !
[55036.513668] windfarm: Overtemp condition cleared !
Here it looks that my CPU frequency is temporarily reduced (at the same
time I hear the fan spinning) and if you see the intervals are very
short (only one cycle copy-pasted here, dmesg is much longer)
Riccardo
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