Radeon Driver Power Management Has Room For Improvement

Here is what the reported GPU temperatures were in each configuration. Sadly for the Catalyst driver there was an aticonfig / OverDrive bug in polling the core temperature, which was not realized until after all of the other tests were complete. For the HD 5750 / HD 4550, the low power profile obviously drops the core temperature a great deal, but the Radeon HD 4870 open-source power management support struggles with no measurable difference between the different settings.

The same OverDrive / aticonfig bug prevented the Catalyst driver from not reporting the real-time core frequency to the Phoronix Test Suite, but above is the average frequencies of the Radeon HD cores during the idling process. As can be seen, dynamic power management was not dropping the core frequency during the idle process for any of the graphics cards. For the Radeon HD 4870, the low power profile isn't working and is just being interpreted as the mid power management profile, which explains in part why it's power consumption wasn't much lower with the power management settings.