The 55nm design of the Radeon HD 3870 GPU along with the inclusion of the ultra power efficient GDDR4 memory has payed off here. As you can see, the 3870 does have a very low idle power consumption level, using just 17 watts here. Under load the 3870 also used less power than the GeForce 8800 GT.

The operating temperatures of these graphics cards are important, but also keep in mind that the 70 degree stress temperature of the Radon HD 2900XT comes at a price. That price being peace and quiet, neither of which you will get with the ultra loud 2900XT. The Radeon HD 3870 was a very quiet graphics card, though as a result the operating temperature levels were quite high.