I got 3 x 290 Sapphire a lil bit overclocked...normal power not undervolt with a BeQuite 850w !
Seems fine so far working nonstop no problems at all

Platinum efficiency

http://www.youtube.com/watch?v=HZwI9ZkRg68

That was when setting up the rig... now its kinda lil bit overclocked... dat psu seems rock
I had no doubt to be honest... its Seasonic parts into Bequite brand