Power consumption
We measured total system power consumption at the wall socket using an Extech power analyzer model 380803. 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 Vista desktop with the Aero theme enabled. The cards were tested under load running Oblivion at 2560x1600 resolution with the game's "ultra high quality" settings, 4X AA, and 16X anisotropic filtering. We loaded up the game and ran it in the same area where we did our performance testing.

Remember, we were forced to use a different motherboard for CrossFire testing, and that will affect system power consumption and noise levels.

The 1GB GDDR4 card again draws less power than its GDDR3 compatriot, and the GDDR4 card pulls fewer watts at idle than anything else in the field. The picture changes a little when running a game. The 2900 XT 1GB GDDR4 consumes just as much power as a GeForce 8800 GTX, but it generally offers lower performance than the GTX.

Incidentally, XFX's high-clock version of the GeForce 8800 Ultra seems to be paying for its high clock speeds and killer performance at the wall socket. The SLI rig with Ultras pulls 586 watts under load. Yow.

Noise levels and cooling
We measured noise levels on our test systems, sitting on an open test bench, using an Extech model 407727 digital sound level meter. The meter was mounted on a tripod approximately 14" from the test system at a height even with the top of the video card. We used the OSHA-standard weighting and speed for these measurements.

You can think of these noise level measurements much like our system power consumption tests, because the entire systems' noise levels were measured, including the Zalman CNPS9500 LED we used to cool the CPU. The CPU cooler was set to run at a steady speed, 60% of its peak. Of course, noise levels will vary greatly in the real world along with the acoustic properties of the PC enclosure used, whether the enclosure provides adequate cooling to avoid a card's highest fan speeds, placement of the enclosure in the room, and a whole range of other variables. These results should give a reasonably good picture of comparative fan noise, though.

For these tests, we had to swap in an OCZ GameXStream 700W power supply. The 1kW PC Power and Cooling unit offers astounding power, but it's a little too loud to use during sound level testing.

I've said it before, and I'll say it again. I'm pleased to see that my subjective impressions are confirmed by the decibel meter. The cooler on the 1GB GDDR4 card is noticeably louder than the one on our Radeon HD 2900 XT 512MB review unit. The 512MB card was an early sample, and I assume the 1GB GDDR4 card is more representative of production cards.

This thing is noisy, folks. There's a nearly 10 decibel gap between the 8800 GTX and the 2900 XT 1GB GDDR4 when running a game. That may not look like much in the graph above, but believe me, it's an awful lot when you're in the same room with it.

Interestingly enough, all of the 8800 cards are sufficiently quiet that, even under load, you won't hear much out of them. I'm pretty certain that what's registering on the dB meter for those cards is the additional noise coming out of our power supply fan, especially when it's straining under the load of an SLI system. Not so with the 2900 XT cards, which overwhelm the PSU fan with their own coolers' noise.

Overclocking
I didn't spend a lot of time overclocking this card, but I did want to see how it would perform at the 825MHz core and 1050MHz (or 2100MHz DDR) speeds of the "OC" version Diamond is planning to offer.

Not bad, but not enough to catch the GeForce 8800 GTX. The card did seem to handle these clock speeds just fine, though. I didn't see any hint of instability or image artifacts when it was running at these speeds.