[ltp] Weird CPU fan problem on T400, any help appreciated.

Pedro Ribeiro linux-thinkpad@linux-thinkpad.org
Sun, 18 Jul 2010 00:51:13 +0100

On 17 July 2010 03:55, Mark Altern <mark.altern@gmail.com> wrote:
> Before Ubuntu 10.04, I was using 9.10 and the cpu fancontrol is working OK,
> without me installing any fancontrol software. I think the BIOS control it
> through acpi. It works perfectly.
> Now after I did a clean install of 10.04, I found the BIOS doesn't do it
> correctly: since the start-up cpu fan speed is about 1886rmp (normal), when
> the cpu temp goes to 55c, it cramp up to 2700rmp, then after that even the
> cpu have been idle for a long while and temp drop to 37c, the fan wouldn't
> slow down, but keep running at that high speed.
> Then as suggested by a linux guru friend, I use a Window 7 install DVD to
> boot the laptop without doing anything, and then reboot back to Ubuntu
> 10.04, this time the CPU fan start working correctly, meaning the fan speed
> goes up and goes down according to cpu temp. BUT, this lasts only for a
> short while, and after running it for a hour, the CPU fan will run high
> speed (2738rmp) without slowing down again, even the CPU temp drop to 36C
> already.
> What possibly is wrong? please give me some guidance, guys.
> Thanks a lot.
> Lenovo Thinkpad T400,
> p8600@2.4Ghz, DDR3@4G, 160G@7200RPM, Intel X4500.

That's strange.. for how long do you have your T400? Maybe you need to
open it and clean the fan.