I overclocked my EVGA GTX 980s in sli to 1317 mhz, and it won't make it through 3dmark Firestrike and Heaven benchmarks before I experience a black screen, where the screen first turns light blue, then black. I am forced to hold down the power button to reboot the computer. I do not see any artifacts during the benchmarks. Does this mean that my graphics cards are damaged, or are they not receiving enough voltage?