Powerbook 12" 1.5 GHz, therm_adt746x, thermal issues
Hi!
I am experiencing heat-caused shutdowns on a PowerBook 12" 1.5 Ghz
(the last 12" PowerBook
model with USB Trackpad and Keyboard) when it is under heavy load and
especially when the Harddisk is
busy (I have replaced the standard HD with an presumably hotter
running 7200rpm drive)
The machine currently runs Debian Testing (Lenny). I have done some
experiments with the options from the
"therm_adt746x" module but with not much success yet. Setting the
"limit_adjust" option seems to effect when
the fan kicks in (default is 50 Celsius) and the "fan_speed" option
seems to be responsible for the initial (or
minimum) speed of the fan when it kicks in.
I am monitoring the temperatures of CPU and GPU as well as the fan
speed while running a CPU and HD
intense task on the PowerBook. The fan is always running at top
speeds when the CPU reaches around 60
Celsius, so everything seems to be alright there. When the CPU temp
stays above 70-72 Celsius for some
time the Powerbook just stops hard.
Now, when I remove the "therm_adt746x" module I get a pretty similar
behaviour in therms of fan management.
The fan seems to kick in a little earlier (maybe comparable to when
using the "limit_ajdust=-7" option) but there
seems to be no temperature shutdown limit (or at least a very high
one). In fact withouth the "therm_adt746x"
module, fan management seems to be exactly like under OS X - how is
this possible? Is it done by the Hardware?
What is the "therm_adt746x" module for then?
I have also looked into the "linux-source/drivers/macintosh/
therm_adt74x" source and found some temperature
limits there but I am not sure wicht ones are responsible for what.
So i did not want to change anything and risk
ruining the PowerBook due to overheating.
I had the same PowerBook running under MacOS X where the CPU
temperature topped out at around 69 Celsius.
I am aware that the sensors might not give exact values but still
they should be identical under OS X and Linux. Is Linux
just running hotter or does the MacOS simply not care about the heat
as much and just not shut down the PowerBook at
about 70 Celsius. Just as I said - i never saw temperatures above 70
Celsius under OS X - i observed about 76 Celsius
when i run under Linux without the "therm_adt746x" module for a while
(then modprobed it in and fetched the temp
from "/sys/devices/temperatures/)"
What I would like to do now is the following: having the fan kick in
quite early and with low speed, increasing the speed
when the temperature gets higher. And i would definitely like to
increase the shutdown temperature limit. Where is this
set and how can I alter the setting? How high could I go with the
limit without killing the PowerBook.
The goal is of course preventing the hard stops because it is rather
annoying when it does i during a rsync backup
to an external Firewire HD for example (and it does this right now...)
I would appreciate to hear any help, suggestions or experiences with
this kind of problem!
Regards,
Andreas Schreiner
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