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. The idle measurements were taken at the Windows desktop, and cards were tested under load running a loop of 3DMark05's "Firefly Forest" test at 1280x1024 resolution.

Please note that these numbers aren't as pure as the driven snow. Because we wanted to include CrossFire and SLI, we kept each brand of cards with its respective platform here, the ATI cards with the Radeon Xpress 200 motherboard and the NVIDIA cards with the nForce4 SLI mobo. Differences in power consumption between these motherboards will influence the overall result.

Even with the caveats, I think we can draw some provisional conclusions. Systems based on the new Radeons uniformly draw more power than the NVIDIA competition, which isn't entirely a shock given the higher clock rates for the ATI GPUs. The system based on the Radeon X800 XL, which has the lowest clock speed of the three, has power requirements under load similar to the GeForce 7800 GT-based rig. The X1800 XT system, with its stratsopheric GPU clock speed, requires 25W more system power than the nForce4/GeForce 7800 GTX system.

These new Radeons also seem to draw quite a bit more power at idle than the GeForce cards—or the Radeon X850 XT, which is on the same motherboard as the Radeon X1000 cards. The X1800 XT, in particular, is pulling an awful lot of juice. The R500 GPUs do clock gating to reduce idle power consumption, and they also ramp down clock speeds a small amount when the GPU is idle. Still, I wish ATI had used more extensive dynamic clock speed adjustments to help cut idle power use further.

Noise levels
We used an Extech model 407727 digital sound level meter to measure the noise created (primarily) by the cooling fans on our two test systems. The meter's weightings were set to comply with OSHA standards. I held the meter approximately two inches above the tops of the graphics cards, right between the systems' two PCI Express graphics slots.

The sound levels the meter picked up track pretty well with my perception of the X1000 series' coolers. The two X1800 cards are reasonably quiet. The XT's dual-slot cooler can be loud when it kicks into high gear as the system powers on, but otherwise, it just whispers. I suppose it might crank itself up inside of a warm case, but it was a model citizen on our open test bench. The X1800 XL, though, had an annoying habit of kicking its cooling fan into high gear for no apparent reason when idle on the Windows desktop.

The X1600 XT is another story. This is a loud card all of the time, whether idle or running a game. The fan just runs fast enough to make quite a bit of noise all day long, more than either of the X1800 cards do under load. ATI may need to put a beefier cooler on this one in order to keep fan speeds in check.