As has been said, your CPU is the bottleneck. Don't worry about RAM, you'll barely see an increase with that. I use the same GPU and get over 60 fps all the time. Try upgrading to an i5 2500k, they OWN.
My specs:
560 ti 2gb
i5 2500k @ 4.5ghz
16gb Corsair Vengeance 1600 RAM
You have a great GPU that should be able to power through this game and pretty much every other modern game out now.