ATI Radeon GPU power management in Ubuntu Natty

Update: Some YouTube videos don't work on the mid setting for me, high seems to be needed. More investigation required!

OK, CPU scaling wasn't the reason for my laptop's excess heat and fan noise after all. The problem was with the GPU.

A forum post outlines how to scale down the GPU to reduce power, heat and fan noise (found via a comment in a Launchpad bug report). Worked for me with the mid power setting.

$ sudo -i
# echo dynpm > /sys/class/drm/card0/device/power_method
# echo profile > /sys/class/drm/card0/device/power_method
# echo mid > /sys/class/drm/card0/device/power_profile 

After applying this change there was a marked decrease in fan noise. The GPU temperature has clearly come down.

Before:

$ sensors
radeon-pci-0100
Adapter: PCI adapter
temp1:       +66.5°C

After:

$ sensors
radeon-pci-0100
Adapter: PCI adapter
temp1:       +56.5°C