Currently running 2 x XFX 7950, on Asus CF board and AMD A4 CPU all under clocked (GPU700MHz, MEM 600MHz) and under volts(0.950V) @734 Mhash/s, CGminer.

Total system power draw @734Mhash/s = 330Watts

Default clocks - 850Mhash/s = 450Watts

Flat out but stable, temps 80C, fans screaming,  @1084Mhash/s one card 1150MHz other 1050MHz = 675Watts