Need to upgrade system to improve source games fps [UK]

[cheetow]

I'm playing CSGO and dota2 mainly and I get around 110 fps on csgo and about 50-60 on dota 2.. this is all on low settings which I like. I want to improve my fps a little more to about a stable 200 so I can purchase a 144hz monitor and make use of it. I have concluded that my CPU is bottlenecking my performance because no matter what quality i set the graphics the fps stays the same.
specs: N68C-GS FX motherboard 8gb ddr3 1600mhz ram gtx 550ti amd phenom II X4 840 3.2ghz
could someone recommend what cpu I should get? Also, is it worth upgrading the motherboard? I know it's a basic one, but I only have basic needs and don't want to spend a lot.
My budget is around £150, thanks

 

[ulysses35]

Im confused... the FPS you are getting are good, but this is mainly due to the low settings you are using. Why do you need higher FPS when you would have a much better experience with lower FPS but at higher settings ? Anything above 40 FPS are playable frame rates. You could play at 200 FPs but the games would look like something from ten years ago.

 

[cheetow]

im not playing for the graphics I want as high fps as possible, so what should I buy.