Should be enough for Battlefield 3. Game is not that demanding.
You should see average 55 FPS with occasional drops on heavy scenes to around 40 FPS. It should stay steady enough at most of the time though. You can enable Vsync to cut out the tearing effect.
I would recommend shedding a bit more on CPU though, get FX 8350 instead of that CPU. Its good, but the other one is much better.