How to make use of Graphics Chips Power Management features
DynamicClocks in the Radeon Xorg driver
The xorg X server has support for a power saving feature from ATI called PowerPlay. Xorg calls this feature DynamicClocks. It can be enabled in the server by adding Option "DynamicClocks" "on" in the Device section in /etc/X11/xorg.conf
Section "Device" Identifier "Videocard0" Driver "radeon" VendorName "IBM Thinkpad" BoardName "ATI Radeon Mobility M9" Option "DynamicClocks" "on" EndSection
With this option enabled, the X11 server should print (/var/log/Xorg.0.log):
(**) RADEON(0): Option "DynamicClocks" "on" (II) RADEON(0): Dynamic Clock Scaling Enabled