That is exactly the problem. It is a waste of a 280x, because the 280x will not make up for the poor CPU. A common misconception is that if you have a powerful GPU, that it will make up for a poor CPU. This is not true at all. If you get 20 FPS with a 6800k, adding 10 780 ti's in SLI will not get you any further than 20 FPS.