[ltp] Re: Fan not shutting down in T40 (Roman Joost)

[ben lamothe]

I have a T40 as well, and I am experiencing the same problem, but I
don't think it's a bios issue, because when placing the cpu under
considerable load from within windows, the fan very seldomly comes on. 
On the other hand, leaving the machine totally idle in linux after an
Xserver is started, the fan generally starts after about ten minutes. 
I've also found that acpi keeps the fan off for much longer than apm,
and that the fan never comes on if the machine is left idle after boot
on a blank login prompt without X, but even if a simpule startx command
is issued with nothing else, within ten minutes, the fan kicks in.  i've
seen this happen for temps as low as 95F, while under windows, the fan
stays off for temps well above 110, while doing computationaly intensive
tasks.

Another thing that I have noticed is that once the fan comes on in
linux, it stays on, even if the temp is as low as 80-85F, while in
windows, in the rare occasions that the fan comes on, it usually
switches back off within five minutes, when the temperature is lowered.

What can be the cause of this, well I am no expert on cpu cooling, so my
guess would be that there is some propreitary windows fan driver that
IBM just hasn't made available for linux, or that linux, or more
specifically XFree86 has terrible cpu management and requires the cpu to
run much less efficiently while executing its binary, while windows has
exemplary cpu management.  I don't think that it is the latter because
this problem has not, AFAIK, been exibited in other machines, and
because linux is superior to windows in *every* way:).  Can anyone else
shed some light on this?

> AFAIK, its IBMs fault, because the BIOS says the fan to turn on at 35C
> which is of courese stupid. I've the same problem and it seems, that
> there is no solution for this untill IBM fixes the fan control in the
> BIOS. This is related to the weird fan noise, which was mentioned by
> many T40 and T40p users ...