Needing a CPU Upgrade?

So my current build I've been running :

AMD Athlon II x4 631 2.6 GHz (OCed to 4.0 GHz) 

Asrock Extreme6 FM1 MB

12 GB RAM, Corsair Vengence/G-Skill

 ICEQ Turbo Radeon 7870

500 GB HD

 

 

I've been told by a few people that the CPU is what is causing my FPS lag in some games, I've thought for a while that it might be RAM or the size/speed of the HD (I upgraded from 4 GBs to 12, showed a little improvement). I've also been recommended to pick up a SSD as that would speed everything up as well. I'm looking for ways to improve FPS on High/Max settings to be 60 FPS or greater. And any way to improve my Windows 8 start up times.

Parts I've considered, AMD FX-8350 or possibly an Intel CPU as I know there is always the argument over which brand has a better speed for the cost. Just looking for ideas and suggestions. 

Hyper 212 EVO Heatsink
RAIDMAX HYBRID 2 RX-630SS 630W

G.Skill 4GB 1333   /   G.Skill 8GB 1866

Thanks to NewEgg! xD

 

Game wise, it seems to vary. I know for whatever issue, Killing Floor is one. Another one is Chivalry. And Arma 3 every now and then.

I'm fine with settings on High. Playing at 60 FPS is a must. Anything below that gives me headaches. The average FPS is around 30-40 once I get into major games or 'battles'. Yes I'm playing on 1080, so possibly lowering that might help? I had not thought on that. Drivers are update to I believe, I'll shall check them here in a few.

Same. I just tried lowering the resolution and I'm hating it. I also went through and re-FPSed every game and found that Chivalry is the worst one. It runs around 30 when not moving and drops to 10-20 depending what all is going on. I've OCed the CPU, but I used AMD Overdrive since it was the easiest. And for whatever reason, if I set the CPU to 4.0 myself, it wouldn't start up. I'm trying some .ini tweaking, since it seems to be the only game that just completely unplayable.