Specs: Maximus VII Ranger, 4690k, 8GB Ram, 1x Powercolor 290 PCS+ (planning to add the 2nd), Xonar D2X, D5 pump, about 12 fans. Overclock on CPU and GPU as well.
Are you sure about the 850W? I was thinking more along the lines of the 1kW model since 2 overclocked 290's will pull quite a bit of power if I'm not mistaken.