I input your system specifications in this:http://extreme.outervision.com/PSUEngine
and put 560 ti because it seems you are inclined with it. The recommended PSU wattage is 368w. So it looks like you can given that you got the 2x6PIN connector in your PSU. I would say it is a bit pushing it but I think it is okay.
Try the calculator yourself with other options to get the graphics card that will match both your need & budget within your PSU cap.