everything on high easily, i got a 6770, i3 2120, 4gig ram and i set it to auto and it puts everything to high expect for AA deferred is off but AA post is High, Ambient conclusion HBAO, Anisotropic filter 16x and Motion blur on.
im running 1600x900 resolution though dont know if that is much different from 1680x1050.
My rig in my sig runs BF3 on High with some ultra. That CPU is good and the 6850 is sexy. The 6850 is easy to overclock with software such as MSI Afterburner or Saphire Trixx. That can give you even more FPS if you are able to OC.