Holy Hell... WR2 is correct! Having 2 x OC GPU will eat more power. Therefore, you will need a Silver / Gold 80 Plus PSU @ around 850~900W. Also, from what I am looking, you are also running intel i7 processor with powerful 8GB ripjaw Memory! These are also power hungry components...
For a system using two GeForce GTX 570 graphics cards in 2-way SLI mode NVIDIA specifies a minimum of a 800 Watt or greater power supply that has a combined +12 Volt continuous current rating of 56 Amps or greater and that has at least four 6-pin PCI Express supplementary power connectors.
56 Amps is the minimum needed to handle a gaming load.
If you want your system to be able to run FurMark or OCCT GPU:3D or any other similar GPU stress testing tool, a minimum of a 850 Watt or greater power supply that has a combined +12 Volt continuous current rating of 70 Amps or greater is recommended.
CPU and/or GPU overclocking will increase the minimum +12V amperage requirement even more depending on the magnitude of the overclock.