I played the last BWE2 with my lesser 560 Card (weaker than 560ti) on my i7 2700k@3.5ghz, 16gb ddr3 ram 1333mhz. I played at ultra settings and not even one hiccup. It ran buttery smooth. At first i wanted to upgrade my 560 but now ill be sticking with it for launch and until some xmas deals come for better GPU's.
In BWE1 i was using a Q6600 with only 4gb ram using the same 560 and running high settings in intense areas cause some slow downs. so its definitely CPU reliant.