Make sure that your Video card is properly plugged in first. Then check your the 6 pin connector. There should be a problem there somewhere. Your PSU is more than enough for the 560 Ti. If there is an option to turn off the iGP on your mobo, you may try that as well.
If that does not work, I gues you may try to use a different Mobo or Video card just to isolate where the problem lies.