Radeon Driver Power Management Has Room For Improvement
In this first test, the various sensors were probed while the system was simply idling at the desktop for several minutes. The default Unity (v3.8.10) desktop was used with the Compiz compositing window manager.
As can be seen right away, with the newer hardware the Catalyst driver consumes less power than using the open-source driver in any configuration. With the low power profile the system power consumption was close for the Radeon HD 5750 and Radeon HD 4550, but with the Radeon HD 4870 the Catalyst driver consumed 20 Watts less than the open-source driver on its low power profile.
Interestingly, using the dynamic power management had failed here to save power and was consuming as much as the default Radeon driver configuration. The Radeon HD 2400PRO graphics card would not function when forcing any power modes. There would be screen corruption followed by the system ultimately locking up within several minutes. Between the open-source driver's default mode of operation and the low-power mode, the Radeon HD 5750 power consumption drops by 26%, the Radeon HD 4870 only by 12%, and the Radeon HD 4550 by just over 5%.