Yes the fan is usually controlled via the BIOS based on a temperature probe
reading from somewere in the laptop. Mine only turns on when I do some really
strenuous under linux (like recursively recompile the kernel 50 times) so you
probably just haven't stressed it enough under Linux. Other possibility is that
the probe might be next the MPEG decoder or DVD drive so it activates
prematurely when playing a DVD (mine gets real hot in this case but the fan
doesn't normally turn on, under Linux its always cold). As for actually
controlling the fan, APCI4Linux is suppose to be hacking support for ACPI
compliant BIOS to control fans, read temps, etc. You can find a link on the
Laptop-HOWTO in section 6 (the link is kind of long and ugly). I tried to take
a look but they appear to still be in heavy development and their CVS-WEB script
has an error and won't work for me. The mailing list seem to suggest their
having atleast partial success.
Remember - Google is your friend, a quick search netted me this, a more indepth
might get you something more useful.
Adrian
