In bf3 with my old gtx 590 I was getting around 80-90 fps, I have just overclocked my CPU to 4.0 and if anything it only gave me only an extra 5-8 frames. If I purchased the rampage extreme iv and a 2011 extreme CPU will it be ok then, would I notice much of a difference.
just take a step back and stop trying to throw money at this problem. no buying the most expensive cpu and motherboard you can get will not solve the problem any more then a 3770k cpu and 125 dollar motherboard. it sounds like to me that you are getting to your cpus limit of how much it can output.
try this. lower your graphics settings in bf3 to low and note the fps. if they are not much higher then your cpu is holding you back.