well between your ram hitting 90% usage your CPU at 80% usage I see a few things going on here. Your ram needs upgrading and your CPU isn't quite bottlenecked at 1080P. If you were hitting 90+% then I would say it was a CPU bottleneck. Try lowering your resolution to the lowest as well as all settings. Whatever that frame rate is your CPU is always capable of, assuming your GPU can keep up. Your GPU may not be keeping up. What is your GPU utilization while gaming? If it is not hovering near 95+% then that may point to a CPU bottleneck as well or you may need to reload your drivers. Personally I think your CPU should be fine for a 60+ FPS frame rate. Your GPU should be more capable then the 20-50 your getting on low which leads me to...