Pc upgrade

last year i bought my console killer pc, but i find it's a bit too bad to play new gen games (bf4,dayZ)
so with my birthday i less than a week, what upgrades shall i get


current specs:

cpu: AMD athlon II 750k

gpu: AMD HD7770

ram: 4GB ram, 1600mhz

psu: 450W


current steam+origin games:

Arma 2

Arma 2 OA




Payday 2


Civ 5

Ghost Recon Future Soldier

Batllefield 4

Battlefield 2

more ram. maybe a better graphics card.

If I'm not mistaken, Arma and DayZ are extremely CPU dependant, and as such Intel's per core performance is about the only thing that will speed those particular games up... 

But overall, I'd be happy with 8 GB of Memory and a big GPU upgrade