Need a new PSU

Hello I have been running into some strange issues with my PC and I assume its a issue with my power supply, I just recently bought a second 7950 and my computer cannot run with both of them in crossfire. I have a Antec 850w that is around 5 years old now. It is missing most of its modular cables so I had to use 2 Molex to 6 pin adapters to get both of the GPUs plugged in and when I tried to run them in crossfire the computer freezes often and will just shut itself off wile under load. When I try to turn Xfire on or off via the CCC It displays a black screen with a blinking white "-" in the top left corner and Im not sure what that is about. I recently upgraded my motherboard and CPU and those have been working wonderfully I just assume my PSU is getting old and unreliable. So I need a new PSU that will run all my stuff wile they are overclocked my system is as follows

MoBo: Asus Crosshair V Formula-Z 
RAM: G.SKILL Ripjaws Series 8GB (2 x 4GB) 1600 
CPU: AMD FX-8350 Vishera 5.0GHz Eight-Core (H100i) 
GPU: 2x Sapphire Radeon HD 7950 3GB Crossfire

I have 3 Sata HDDS for storage and 2 SSDs running striped for my OS and important programs drive. I have been looking at the Corsair 850w but they have so many different ones Im not sure what one to get.

If its the old Antec design that Im thinking of they had a quad rail setup, and the amp distribution was pretty shit from memory something like only 40amps or so combined 12v rail output while big number for 3.3v. and 5v rails.

OP what model is it exactly? If it something like the fiqures above you'll have to get another unit to run crossfire. It is probably down on power anyway since its getting a little old. A good Corsair 850 (AX if you can afford it) or something from Seasonic, XFX (seasonic rebrands), even the new Antec HCG's are really nice units (seasonic rebrands as well.