In case it has not been resolved.
The EVGA SuperNOVA NEX750G PSU is supposed to come with four 6+2 pin PCIe connectors and four 6 pin PCIe connectors I understand.
Your video card requires two 6 pin connectors, so you should use two of the 6 pin PCIe connectors. But there was mention of only 6+2 pin connectors being available? Did the 6 pin PCIe connectors get lost?
To use the 6+2 pin PCIe connectors instead of the 6 pin PCIe connectors you just detach (carefully) two of the pins (within a connector) which is clipped into the side of the remaining 6 pin connector, and move the two detached pins aside. The remaining 6 pin PCIe connector is then plugged into the video card.