On ultra I don't think your build stands much a chance for getting decent fps sorry to say. Battlefield 4 isn't the most optimized PC port to begin with and just looking at the recommended specs: http://www.battlefield.com/battlefield-4/faq
, I would say your CPU is nowhere near powerful enough and you GPU would probably be OK at best if it had a great cpu to rely on. If you get that new cpu and OC it it may be able to work at a decent framerate. As I think your build would probably work well on mid-high graphical settings but not ultra.