Power Consumption And Noise
Both of AMD’s Radeon HD 6900-series cards give us power profiles that look a lot like existing boards in our three-loop logged run of Metro 2033 at 2560x1600 using Very High quality settings, 4x MSAA, and anisotropic filtering. The Radeon HD 6970 is very similar to the GeForce GTX 570, and the Radeon HD 6950 traces very close to the Radeon HD 5870.
A closer look at the averages confirms this. The Radeon HD 6970’s average system power in this test is 321 W, while the GTX 570-based system consumes 329 W. The Radeon HD 6950 averages 279 W and the Radeon HD 5870 averages 274 W.
When the Radeon HD 6900s aren’t in use, they throttle down to a 250 MHz core clock and 150 MHz memory frequency, saving power.
Nvidia stepped it up with regard to the thermal and acoustic management of its high-end cards. After the poor reception of GeForce GTX 480, both the GeForce GTX 580 and 570 were able to top performance charts and come in at the bottom of our noise benchmark.
AMD’s Radeon HD 6970 and 6950 also show well in this regard. Though the GeForce GTX 570 remains the quietest card in our comparison, it’s followed closely by the Radeon HD 6950. A couple of other configurations slide in ahead of the 6970, but it’s also a very subtle presence in any performance PC.
The one caveat I’ll throw down here—and this really has to apply to any gaming machine—is that you want these cards at least three expansion slots apart if you’re planning to go with a CrossFire setup, leaving enough room for airflow between the first and second boards. Should you cram them back-to-back, expect much less desirable acoustics. We measured a pair of Radeon HD 6970s at 53.9 dB(A), compared to two GeForce GTX 570s at 49.6 dB(A) in such a not-recommended configuration. While I've been talking about four slots worth of expansion dedicated to dual-card setups up until now, it's really more realistic to think of any CrossFire or SLI array as needing to populate five slots.