the 780 ti will run all 4 displays just fine. You will be able to run all of your displays at native resolution smoothly with no problem at all (assuming you have the correct cables, and decent cpu) As for gaming in surround, you will be able to play games on high, some on ultra with no problem. Not sure what nuclear meant, but the 780ti will be a huge improvement over your 560ti, and will tear through games in surround.
Edit: I misunderstood. if your not planning on gaming in surround then you will max everything, with ease. As for standard desktop mode my 780 idles at around 5% with 4 displays (1680x1050). Gaming performance on one monitor will be unaffected by having the other 3 connected, and if you do game in surround you can use...