well the a8 5500 isnt a bad processor ,still its not a fit for a 780
i would go for 8350-the 8 cores will help you to make some video editing (if you do any)and lets say BF4 takes advantage of more cores.
and the higher clock speed isnt bad either.
its way faster and 30$ cheaper,maybe now you would prefer it
you can also go 8320 which is another 40$ cheaper,but i dont think you should miss out from the 8350 performance