Power consumption
We measured total system power consumption at the wall socket using a watt meter. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement. We tested all of the video cards using the Asus P5N32-SLI SE Deluxe motherboard, save for the CrossFire system, which required a different chipset. For that system, we used an Intel D975XBX motherboard.

The idle measurements were taken at the Windows desktop. The cards were tested under load running Oblivion using the game's Ultra Quality setting at 1600x1200 resolution with 16X anisotropic filtering.

Power consumption at idle is quite good for all of the single-GPU systems. When running a game, though, the ATI cards simply require more power. The Radeon X1900 XT pulls 75W more under load than the GeForce 7900 GT, and the Radeon X1950 XTX out-pulls the GeForce 7900 GTX by a similar margin. The one bright spot for ATI here is the fact that the Radeon X1950 XTX draws 17W less power than the X1900 XTX. Apparently, the combination of R580+ and GDD4 memory has the potential to reduce power draw somewhat.

One reason that the power draw is relatively low for the X1950 CrossFire system at idle, by the way, is the fact that the Intel motherboard supports the Core 2 Duo processor's C1E enhanced halt state, which cuts the CPU clock speed at idle. The P5N32-SLI SE Deluxe doesn't appear to support C1E halt, so the CPU draws more power when sitting idle on that board.