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 5870/5850; coming in with the lowest idle consumption of all the cards that we tested. What’s more is the idle power of 5870/5850 in CrossFire, drawing less power than a single HD 4890 and just 18-20W more than a single GeForce GTX 285. In CrossFire, the Radeon HD 5850 system approaches 500W under full load, which is 100W less than the Radeon HD 5870 CrossFire setup. 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.