I played BF4 with an 8320 at 4.0 for more than 1 year. Smoothness side it is uncontested, the game behaves really well on 64MP. The problem is that if you use DX11 on that game your FX wont be able to assure you +75fps at all times (i have a LG IPS panel OC'ed to 76hz so it is kind of a big deal for me to sustain that many fps most of the time) and it will totally dip to ~55FPS on some portions of the most played vanilla maps (this happens if you use MESH QUALITY and TERRAIN QUALITY on high/ultra). Also, on DX11 I had better min framerates on a 760 than a 7950 TB. So in my experience, in min framerates and DX11 NV has the lead.
So my TL;DR here is: On a FX on DX, you will have smooth gameplay but if you plan to have sustained high FPS, drop those 2 settings to med/low because they will make you dip into 50-55 FPS in specific portions of some 64MP vanilla maps.
PS: I played with mantle too and perf increase with those 2 settings on ultra is very welcomed, I would sustain 75 FPS with mantle ON. Smoothness/frametimes were improved too. But you will feel bad when you realize that after some patch they locked down the CPU threading commands and with an FX 8xxx you wont be able to use more than 6 threads. Removing 2 threads from task scheduler when playing BF4 MP incurs in zero performance loss in my personal experience. But oddly, disabling a module to achieve a similar effect made the game really less smooth in the frametime department. Kinda odd if you ask me.