I have a GTX 670 but an i7-3770k and it never dips below 60 fps for me
my processor makes the difference though
edit: you bought a 670GTX for $390 right before 770/780 GTX were coming out as way more powerful cards.. for the same price.. thats no one bad decision for but yours..
Just because
YOU PERSONALLY bought a card THIS year doesnt mean that card hasnt been out awhile.. that card came out in like May of 2012..
edit: yup May 14th
2012 is when the 670 GTX came out
edit #3: You bought the 670 GTX for $389, literally right before the 770GTX came out May 30th for $399.
the 870 GTX will probably come out May 2014.. guess how much it will cost? You guessed it? $360-400.
PS I bought the 670 GTX for $360 mid-late 2012, no idea why you spent $390 on a card that was out a year

next time if you need help building your computer just ask