For our power testings we utilized our Kill-a-Watt EZ to measure overall system power consumption in three states. For the first state we let the system idle for 15 minutes and then took a reading. The second state we ran the Aliens vs Predator benchmark and took an average maximum reading. Finally for the extreme not real world test we ran furMark 1.9.1 for 15 minutes and averaged the maximum readings.
The Kill-A-Watt is a simple device you plug into the wall and then plug your system into the port on the front. It then provides real time watts, amps, or other electrical readings.
The ASUS GTX 570 DirectCU II places in the middle of the pack and surprisingly is slightly better with power during gaming than the Radeon HD 6970 and 9% better than the Classified version of the GTX 570. However, if you run FurMark which throws every possible OpenGL command at the card at once you can get this FERMI to peak out higher than the 6970. This is totally unrealistic because this would only happen in this stress test but it is good to see how the cards handle power.