During our conversations with AMD on the Radeon HD 6000 series of video cards it was crystal clear that one of the goals in mind was improved performance per Watt.
AMD says they met their design goals as the AMD Radeon HD 6870 uses less power at idle and the same amount as the ATI Radeon HD 5850 at peak load. What is also interesting is that the AMD Radeon HD 6870 has slightly better performance than the Radeon HD 5850, yet has 25% less silicon in use as the die size is smaller.
For testing power consumption, we took our test system and plugged it into a Kill-A-Watt power meter. 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 1.8.2 at 1280×1024 resolution.
Power Consumption Results: The AMD Radeon HD 6870 cards that were built off the reference design were close to having the same power consumption. Since each chip is going to have slightly different leakage the numbers will not be identical for any two video cards even if they are on the same design. We have been told that even chips from different spots on the same wafer will have very different power testing results. The Diamond Radeon HD 6870 XOC video card used the most power at load, but this makes sense as the card is factory overclocked.