My current system:

I5 3570 CPU
MSI 4gb GTX 960 GPU
8 GB Ram
ASUS P8Z77 Mother Board
GS800 Power Supply

Upgrade that has already been ordered, but waiting to install:

I7 3770 CPU

Everything on max settings runs at 60 FPS even in heavy content. Word of advice, do not let your GPU's stock fan controls stay. Adjust the fans to continuously run at lower settings instead of the stock controls setting the not run at casual settings. It's more wear and tear on a motor to have to start and stop a fan over and over as it hovers above and below the threshold than to let them run at a low setting continuously then speed them up when the load increases.