Yes I was mainly concerned that an i3 would be quite slow and maybe you should consider replacing this as well. However it is completely up to you.Think he meant CPU, that i3 is a few years old now, and i3's aren't really ideal for most gaming rigs. The most important factor would be what power requirements your psu could handle. What wattage is yours?
The 900 series draw quite little power and so a 960 should take less power than your current 560 se. You may even be able to cram a 970 in there.
Is gtx 760 good enough? I can get I5 processor for 200 dollars