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 5 minutes and took the reading. For load numbers we measured the peak wattage used by the system while running through 3DMark 2006.
As we noted with X1950 Pro, the shrink to 80nm helps out here as the X1650XT Pro uses less power than anything else we were able to test at idle. Under load it consumes slightly more power than the 7900 GS and 7900 GT. Not exactly great performance per watt compared to the X1950 Pro.
Unfortunately we only have a few SLI systems to test against so the X1650XT CrossFire looks really good here. I’m still amazed at just how little power the 7950GX2 consumes! It’s still by far the performance per watt champ.