Crossfire 7970 ASUS DCUII/XFX DD 7970 and Corsair GS700?

I can get a XFX Double D 7970 for $250 to crossfire with my asus 7970, the asus card uses two 8 pins which uses both of my power supplies pci-e 6+2, and the xfx uses a 8 and 6 pin, would this power supply be enough to power both plus my overclocked 8320 and everything else? If i used Molex to pci-e a single 8 and 6 on the xfx card would the psu be enough to power that off the molex cables? and enough in general?

This is the psu since theres two versions of the gs700 - http://www.corsair.com/en-us/gs-series-gs700-80-plus-bronze-certified-power-supply-2013-edition
 
Would the XFX 850watt Pro 80+ Gold fully modular be good then? Saw a chart of full load extreme i7 with crossfire 7970 during furmark to be 650watt fulls system and gaming was slightly under 500watts, obviously my psu may not fully put out 700watts but thats quite a bit of a difference