The Radeon HD 7900- and 7700-series cards have already shown us the 28 nm manufacturing node’s implications for power. AMD claims its 7800s are similarly efficient.
At idle, sitting on the Windows 7 desktop, both 7800s deliver the lowest system power results of the cards we tested.
In addition to their low active idle power, the 7000-series Radeons benefit from a suite of features collectively referred to as ZeroCore. When a display connected to one of these cards drops into standby mode, the card is able to spin down and shed another 10 W or so of power consumption. Compare the Radeon HD 7800s to Nvidia’s GeForce GTX 580, which drops a single watt, and still consumes more than 40 W as our test PC sits idle.
AMD’s Radeon HD 7870 uses significantly less power than Nvidia’s GeForce GTX 580, while achieving similar results. That comparison typifies what we’ve seen from some of the other 7000-series boards: competitive performance at markedly lower power.