Note if you are overlocking you had better have damn good connections at the PSU and the Titan. The one I was overclocking was soldered directly to the Titan cube using TWO high quality 6x PCI-E connections (NOT the cheap square pins with the split down the middle).
Which pins are those? The split is the as that is how the pin is folded when made.
The good pins have a dome shape on one side of the pin and only one split. The crappy ones are square with two splits. My PSU's over 1200 watts seem to have the good ones, the other 8 PSU's I have, don't.