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 game S.T.A.L.K.E.R. – Clear Sky at 1280×1024 resolutions with high image quality.
Power Consumption Results: The Radeon HD 4890 1Gb uses less power than a Radeon HD 4870 1GB at idle, but more at load. This shows that the improvements that AMD did to the RV790 core paid off as they were able to drop power consumption on a video card that has higher clock speeds and voltage requirements. At load the Radeon HD 4890 uses more than a Radeon HD 4870, but this is due to the higher frequencies and voltages. The GeForce GTX 275, on the other hand, had the same idle Wattage as the GeForce GTX 260 Core 216, which was amazing seeing how it has 240 shader cores. At load the GeForce GTX 275 uses more power than the GeForce GTX 260 Core 216 though, so NVIDIA did something to get the idle power consumption down. The NVIDIA GeForce GTX 275 also has the highest power consumption of the group, but just by 3W.