Introduced in ATI's v8.19.10 proprietary display drivers for
their RADEON series was support for PowerPlay. For the uninitiated,
ATI's PowerPlay allows the user to specify various "power-states", or
rather various frequencies and voltages at which the card can operate.
The purpose for these various performance levels is ultimately to allow
mobile users to save on battery life through running at reduced speeds
when not performing strenuous 3D tasks. Read on over at Pyro CPU.