Open source ATI Video card works quite well these days. I try it for stability reasons. There could be some problems left.

Continuous high fan speed (solved)

Source:

sudo apt-get install sysfsutils
sudo gedit /etc/sysfs.conf

Possible values:

   class/drm/card0/device/power_method = dynpm | profile

And additionally if you picked 'profile' method:

   class/drm/card0/device/power_profile = auto | low | mid | high

Note: dynpm (dynamic) would be nice but it only does mid and high fan speed, not low. So I added these two lines to '/etc/sysfs.conf':

   class/drm/card0/device/power_method = profile
   class/drm/card0/device/power_profile = low

Anonymous