tecdomination

Hi, i own a vibox with a fx 4170 cpu that runs at 4.2ghz that is installed with a radeon hd6670 graphics card. I have upgraded the psu to a corsair 850w psu and i have swapped out the fans aswell so far, my goal is to upgrade the pc step by step untill i get to a new pc. I have a radeon 480 xxx oc on the way and i was wondering if there is a better cpu i could put in to minimize bottlenecks while i get the funds for a new motherboard, cpu ram and cpu cooler. This is all the parts i will end up with on pc part picker https://pcpartpicker.com/user/DTFG_ZERO/saved/vfGkJx