I am running two GTX 660ti's in SLI, that require two 6-pin connections each. (total of 4 needed). I have a 1000w Cooler master modular psu. This PSU comes with 3 fixed cables, two are 8pin mobo cables and one is the 24pin mobo cable. I have the 24-pin and one of the 8-pins plugged in to power my mobo (which is a gigabyte z77x-up5-th) which leaves one of the fixed 8pin cables free. I was wondering if I am able to use that second 8-pin cable with a 6-pin extension cable to power one of my GPU's?