Hello I just recently built my first rig and I want to add another graphics card, I have a corsair 860W platinum psu, my current specs are a 4770k @ 4.4ghz, gtx 780 (gigabyte Ghz Edition), 16 gb ram OC'd at 2133. Will it be enough to at another card and not need to buy a different psu? I want to add another one of the same non reference card.