Re: G4 Powerbook System Fan UBUNTU Feisty
By default the therm_adt746x module lowers the maximum temparatures. But
you can control this with the module parameter "limit_adjust".
That said I'm not sure if it's wise to increase the maximum
temparatures, because it could damage your hardware on the long run. The
fan on my pb 15" (pb5,8 1,67GHz) does not run (or very low speed) most
of the time. I'm not sure why yours should run significantly hotter.
This is correct but unfortunately the standard values seem to suit the
last (1.3 Ghz and above) PowerBook models as far as I experienced.
This means the fan kicks in relatively late if you use the standard
settings (limit_adjust=0) and the PowerBook gets pretty hot (at least
the 12" models).
You can lower the temperature where the module starts the fan by using
the "limit_adjust" value (setting it to -5 for example) but this causes
another big problem. The therm_adt746x module shuts down the Powerbook
intantly if the temperature reaches a maximum value for some time (not
sure how long but some 10 seconds at least is my guess). The default
shutdown temperature is 70 degrees C at the processor thermal sensor
which will be reached in very processing intense tasks (compiling a
kernel will shut down the PowerBook hard - not a good thing)
The upper temperature limit is also effectet by the limit_adjust value
and setting it to -5 will lead to a heat related shutdown at only 65
degrees C. This temperature can be reached easily in more or less normal
working conditions and renders the limit_adjust option pretty unusable.
Just as a clarification - my experiences are limited to 12" PowerBook
models and maybe bigger models will deal with the heat in a better way.
But one observation I made is that the hardware, without the
therm_adt746x module) can manage its fans by itself - seemingly very
much similar to the OS X thermal management. So unloading the module and
letting the hardware taking care of itself might be a good idea and
should be possible on all of the latest PowerBook generations as well.
If anyone would like to improve the therm_adt746x model I would also not
complain. I looked into the source already but my very limited programin
abilities (no C at all yet) mean that it will be some time before I dare
to change the Kernel myself.