I totally agree about the wattage!
At the moment i have 2 cards in each rig
ASRock 970 EXTREME4 AM3+
CPU: AMD Sempron 145
PSU Corsair HX850 gold
Memory low voltage ( 1.35 ) OCZ 8gb
2 x MSI 7950
Total draw 640 watts and yet tacotime somehow gets 635 watts with 3 cards?
My other rig is an ASUS Z68 pro Gen3 board
with one MSI and a sapphire 7950 and it bascially pulls the same
Tho the sapphire card has far better temps than the MSI cards
I probably average 550 KH/s per card
The power draw from these rigs is killing me!