For testing power consumption, we took our test system and plugged
it into a Seasonic Power Angel. For idle numbers, we allowed the system
to idle on the desktop for 15 minutes and took the reading. For load
numbers we measured the peak wattage used by the system while running
the OpenGL benchmark FurMark 1.7.0 at 1920×1200 resolution.
Power Consumption Results: In
the last few years, power consumption is something that has become an
important part of the overall package of a graphics card. AMD and
NVIDIA have both taken steps to improve idle power consumption to keep
power bills low since that’s where most graphics cards spend their
time. It’s also important to remember that less power means less heat.
AMD has hit a home run here with the Radeon HD 5000 series; coming in with the
lowest idle consumption is very impressive. What’s more is the idle
power of 5870 in CrossFire, drawing less power than a single HD 4890
and just 18w more than a single GeForce GTX 285. Under load, the HD
5870 used just 3w more than a single GTX 285. When you consider how
much the Radeon 5870 outperforms the GTX 285 you can’t help but be
impressed. In CrossFire, the HD 5870 system approaches 600w under full
load. The Radeon HD 5770 and 5750 both idle under 160W! With the GPU at full load using the Radeon HD 5750 the total system power draw at the wall was just 245W! That is the lowest number we have seen to date on our new Windows 7 64-bit test system!
Keep in mind that the less GPU bottlenecked that the system is,
the harder the CPU will work, thus increasing power consumption by the
CPU. In simple terms, not all of the additional consumed power is going
to the graphics card.