From what I understand, the PG278Q needs DP, so you would need 3 cards if you plan on using that monitor x3 in the future. For one display, I have x2 GTX 780 Ti and I can't imagine needing more power for for 1440p. It's already pretty much overkill.
Same thing with mine. 4930k with rampage IV black edition. Bios is up to date and only changes I have made is XMP profile for my Corsair platinum 2133 memory. First step goes to 4.1 and second 4.2 it gives a bsod in windows 7 with either.