Power consumption and temperatures
For the power and temperature measurements, we've added a standard 1GB Radeon HD 5870 to our graphs for comparison's sake.
As expected, the Radeon HD 5870 Eyefinity 6 Edition draws more power. The larger frame buffer is partly to blame, but the cards powering multiple monitors are also unable to reduce idle clock speeds as drastically as the standard Radeon HD 5870, hence the respective rise in idle power consumption when powering three and six displays.
No surprises here, as the elevated power draw and higher idle clock speeds translate to a higher idle temperature. There's little in it when under load, though.
A word on noise
For those that enjoy a quieter computing experience, we found the fan on the Radeon HD 5870 Eyefinity 6 Edition hit speeds of 1,998rpm and remained relatively quiet during a session of Battlefield: Bad Company 2 at 5,040x2,100.
The CrossFire configuration - with two Radeon HD 5870 Eyefinity 6 Edition cards in close proximity - proved to be warmer, resulting in the fans spinning up to a noisy 2,425rpm.