[ltp] t42 archlinux fan noise

[Damien Challet]

> I have been using Ubuntu for a couple of years on an x31 and a t42 
> without any problems. But now I switched to Arch Linux and for some 
> reason

it is probably reason which cause the idle temperatures to rise.

> then fan on my t42 is always running around 3500 rpm even when the laptop is 
> idle for hours (cpu load < 5%). Only very seldomly does it go down to 
> 3000rpm.

what gives acpi -T, or even better 

cat /proc/acpi/ibm/thermal ?

use also powertop to check the likely cause of this.

You should also use hpet=force in /boot/grub/menu.lst which helps keeping the 
CPU idle.

Finally, you can try to  undervolt your CPU if you do not mind a hard crash 
every 3 months.