Good PC, drops to 30FPS, only 30% used

Hi, last few years I was playing cf on quite crusty PC, dual core 3,2GHz, gtx210 1GB(with 30% OC) and 3GB ram.
But for CF that PC was enough, up to 200FPS, and down to 50FPS with 5 smoke grenades in same place where I was, most times about 150FPS.
Now I build better PC, to be able to play new games like GTA V, Witcher 3 etc.
That new one have quad xeon x5450 3GHz 12MB cache, r9 270oc 2GB(also OC my self by about 20%, maximum that MSI afterburner can) and 8GB RAM.
From that rig I was expecting 500-1500FPS.
But its even lower than at my older PC...
Up to 200FPS and down to 30FPS when camping in ONE smoke grenade.
So I tunred-on OSD from msi afterburner to see usage of hardware, there are results(I was going to add SS but I cant on that crusty website):
GPU: memory usage 0%(132MB), gpu processor usage 48%
FPS: 205
CPU usage: 28%, core1 16%, core2 20%, core3 56%, core4 20%
RAM usage: 3005MB
What is going on?
Im quite sure that PC is ok, because I can play GTA V very well at 1080p and high settings...
OFC all newest drivers instaled(insulding DX11).
So whats the problem?
Before I saw these OSD parameters I was thinking that CF only uses two cores and bottle-necking the GPU, but as we can see above, not.

Its nothing important, because im going to stop play CF(too much kids and ahmeds that kick me for "hakr kosomko a7a") but im curious.