Rebuilt a rig today!

3x HD5870 @ 800/300/1.0 Volt = 3x 350Mhash/s
Fans at 50%
AMD Athlon 64 6400+ Black Edition 3200MHz @ 2000MHz (10x multiplier) and 0.975 Volt (undervolted)
400Watt out of the wall socket.
1050Mhash/s / 400 Watt = 2.65 efficiency factor
Software: Windows 7 x64 / CGMiner
Can be tweaked a bit more I guess but first I try it at these settings.
These ASUS CARDS are damn good, had 4 of them. Even when placed tight together they'll stay cooler than others