I am having a bit of trouble deciding on a psu for these ? I currently have a Thermaltake 850 GRAND. Not sure if it can pull 2 GeForce 680+ 4Gb Video Cards (2). Just 1 card needs 38 amps from 12V rail
Thermaltake is an iffy brand for PSU's. Probably can, but it might die sometimes. Personally, I would grab an Antec, Corsair, XFX, or Seasonic 850w/750w and call it a day.
Where did you read that each GTX 680 draws 38A. By my calculations it will draw 16.25 maxed out. (195W ÷ 12V = 16.25)
http://www.hwcompare.com/12344/geforce-gtx-680/