> > http://jcs.org/patches/openbsd-acpithinkpad_fan_control.diff
quoted text
> >
> So i tried it but can't have it working on my machine. Kernel crashed
> at startup.  I'm not sure what I can do to modify it right now.

that patch is pretty old, i'm surprised it even applies and
compiles.

quoted text
> Anyway, to make sure I didn't dream I installed a double boot with a
> linux distribution and while the lappy under linux is really quiet
> (quasi silent), t's really louder on openbsd once I plug it, or plug
> an external screen. Any idea where I can look/need to provide to help
> to fix this behavior?

you're welcome to dig into the linux thinkpad acpi driver:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/plat...

note all the firmware bug comments, model-specific quirks, watchdog
routines and other stuff in 1300 lines of code just for fan control.
this is why my fan control patch is a hack and won't be committed.