So I'm overclocking my graphics card which is a GTX 670 power edition from msi using afterburner. I'm stress testing with Unigine Heaven, the newest version as of this post. I only seem to be able to get my card up to 1228 MHz, as soon as I hit the next step which is 1241, the card crashes about half way through the benchmark. Did I just get a dud overclocker or is there something I can do to change this? I've upped all the voltages to their max values available in the official mode of Afterburner and I maxed the power limit (114%), but still only getting 1228... Please help!