Power, Heat, And Efficiency
The strangest thing about Asus’ power management software might be that, operating at its default mode, the app costs us between 25 and 30 W at idle compared to “Max Power Saving” mode or even Windows 8 running without some form of manufacturer-imposed management. Either of those options drops idle draw into the mid-60 W range. Why not switch to “Max Power Saving” mode exclusively for this test? I don't think it's realistic to expect enthusiasts to toggle between operating modes based on what they're doing. What we're testing here is a more real-world configuration.
That high idle wattage result is particularly unfortunate when we see just how much better the M5A99FX Pro R2.0 is than Gigabyte's 990FXA-UD3 at full load. Default settings appear designed to cap CPU current (and thus heat), rather than maximize performance or efficiency.
As a point of comparison, ASRock’s Intelligent Energy Saver is disabled by default.
ASRock’s multitude of tiny voltage regulator phases does a fairly good job of spreading heat across the 990FX Extreme9’s oversized heat sink.
Asus’ software plays a role in dropping the M5A99FX Pro R2.0 a percent below average, while Gigabyte’s reduced storage performance bends the ends of the curve to put ASRock 2% over the top.
More than anything, ASRock's efficiency lead is a testament to how well AMD’s hardware and firmware manages power on its own, without the intervention of software.