To test power consumption today we are using a Keithley Integra unit and we measure power consumption from the VGA card inputs, not the system wide drain. The best way to get maximum load results is by using Furmark, and even though it is not indicative of a real world situation it shows the limits the card can theoretically demand. The ‘gaming’ results are measured when playing Crysis Warhead – which is a more valuable result to take from this.
The card certainly demands a lot of power under load, however it is interesting to see the idle power consumption figure is rated around 35 watts from our testing. The last HD5970 we tested consumed slightly more than this. Running two of these cards in Crossfire will certainly demand a very capable power supply.