I'm not really satisfied with the performance on my 970. Maybe I'm being a bit too optimistic of what it can do but running the game at 60fps with dips into 40's at times. Have settings mostly on high with some very high and msaa 2x with 3570k at 4.2ghz
It will probably be more to do with your i5 than you gfx card.
The game is very cpu intensive. I don't get full usage on my 980 even at 1080p, everything maxed, vysnc OFF and with 4xMSAA and i have a 4.5ghz i7