[ltp] IBM R51: The always on fan problem

[Laurent Gilson]

Hello

> I am new to this ML. I found it when I was looking for a solution to my  
> IBM R51 on which I installed fedora cr 4 and whose fan is ... well...  
> always on.

There are several problems with the R51 that may cause the fan-always-on  
problem:

The first (and unsolvable) one is the CeleronM. It creates far more heat  
while idleing and triggers the fan a lot. Use a PentiumM.

Severeal others are related to the radeon-gfx. If it's running in stock  
configuration it triggers the fan after 10min. But using the os  
radeon-driver and enabling dyn. clock solves that one. (In the past dyn.  
clock didn't work for the R51, it caused crashes. That is resolved now)

The next common one is speedstep: Without loading the speedstep modules  
for the PentiumM the CPU always runs at the max. frequency. In turn it  
gets very hot and triggers the fan. (You need to setup a governor for this  
to work).

Apart from the frequency all CPUs can enter sleep-stats (called C1,  
C2,...C8, C1 = almost no power saving, C8 = a lot of power saving) to save  
power. If you enable/load the Xserver extentsion GLX the CPU can no longer  
enter stats below C1. So far i don't know why. With all after drivers  
loaded it reaches C3. With a bit hacking you can get C4 (IMHO not worth  
it).

Next problem is the WLAN-card. In default configuration it get's hot quite  
fast. If you enable "Power Management" (see iwconfig) it consumes a lot  
less energy.

If you want more: undervolt the cpu.

cu