The Current State Of Radeon Power Management
Here is a look at running Doom 3 on the Radeon HD 6950. The results when forced to the different performance/power levels are in line with expectations for the clock differences. The Catalyst driver was obviously much faster than the open-source stack with Gallium3D user-space.
The CPU frequency data isn't too interesting, except to note that when the Radeon HD 6950 was forced to its lowest state (250MHz), the CPU frequency via Enhanced Intel SpeedStep Technology also was commonly operating at its lowest power state, likely due to the reduced workload while waiting for the GPU to finish its tasks.
The CPU usage was much higher with the Catalyst driver than the open-source driver. Confirming the previous findings, when the GPU was in its lowest power state, the CPU usage was reduced.