Obviously the fan rpm can be controlled somehow in kernel-level (as we seen in 3.2.x kernels but not 2.6.x). How can I change the speed of the fan manually?

Currently the only solution seem to be finding it from the kernel code.

lm_sensors is useless, I have tried that approach..

I've also posted this question to http://www.linlap.com/wiki/acer+aspi...07c93481a6366a

Thanks in advance!

Thanks for nothing...

Just solved, how to change S3's fan speed writing to embedded controllers' (EC) registers using acer_ec.pl. Here you are…

93 is the fan state (auto/manual), 94 is the input for fan speed, 95 is the read only output for current fan speed.

Remember, using fan other than in AUTO mode WILL PROBABLY VOID YOUR WARRANTY!! So be damn sure what you are doing!

# Set S3 fan to AUTO
sudo perl acer_ec.pl := 0x93 0x04

# Set S3 fan to MANUAL
sudo perl acer_ec.pl := 0x93 0x14

# When manual, set the speed in value 0x00-0xFF (0xFF min vs. 0x00 max)
sudo perl acer_ec.pl := 0x94 0x00

---------- Post added 2012-04-19 at 18:53 ----------

Modified version of acerfand for your S3 ultrabook: http://enyone.rainio.org/homedir/acers3fand/