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 Aliens vs. Predator full video game at 1920×1080 resolution.
Power Consumption Results:
As you can see, running at idle the test system draws 130 watts of power, but once we get the ASUS Radeon HD 6870 to a full 100% load it spikes up to 272 watts, a full 142 watt jump. Not too shabby if you think about it. Even if you had two of these cards in a Crossfire configuration with a 750 watt PSU like our test system, you still have almost 500 watts of headroom.