Very low fps while playing

BF4 has a high CPU usage so if the game starts having problems like framerate drops, stuttering and lag spikes your CPU might be causing a bottleneck. You might be able to overclock your CPU if you haven't already. Your GPU and the amount of RAM should be ok.

Youtube user Holaukko has a worse GPU than you but he has an overclocked 955 @ 3,2Ghz and seems to be playing ok with high settings (Battlefield 4 Gameplay | AMD Phenom II X4 955 @ 3,2Ghz, Asus GTX 660 OC 2Gb): http://www.youtube.com/watch?v=d1SW5d8BeV8&feature=youtu.be

ya i know its bottleneck but the problem just start today and i didnt made any change to my computer. been play smoothly for month

Hmm it could also be a server problem, some players have noticed that sometimes just changing a server their problems have ended so try a different server if that might help.