This is simple enough to test. You say you play bf4 (assuming bf4 over bf3), get something like MSI afterburner, turn all settings to low, use the on screen display to show gpu usage, if it is less than 90% most of the time you are cpu limited. In that situation a new video card won't make a whole lot of difference.
BF3 actually. Good suggestion. What is afterburner? Does it replace Catalyst Control Center? Can I play multiplayer while having the on-screen display on?
I'm kind of miffed that no one has done these kind of tests somewhere on the interwebs. All the review sites seem to test the same configurations and single player and are not very useful to most people. I mean yes BF will run really fast with 4790k overclocked with a gtx 980. But I don't need a review site to tell me that.