What you need to do is monitor your CPU and GPU core clock and usage. At one point I had an issue with BF4 where my GPU was only using 40-60 percent of it's capability. You could be having a similar issue. Use MSI afterburner/rivatuner along with HWinfo64 to display all these metrics on screen while your playing.
You want to make sure your CPU/GPU is running at the clock you have set, temperatures are all in the safe range, and whether your GPU/CPU is actually working hard. If it's just sitting at 60% usage that would explain the low fps.