I have a HP laptop with a AMD 3 core and was reviewing parts for a build. Your post/machine (8320 cpu, 7770 gpu) were two components that I was focusing on. What PSU do you have (ie. watts, # of 12v rails, eff%)?? I was thinking of 500W @85% eff. with one 12v rail.
MicroCenter has the FX8320 for $100; my alternative cpu is FX6300 ($109) or even FX4130 ($60) again all at MicroCenter. If I went Intel, I think I5-4570 ($160) would be selected. Obviously anything that I choose would be much better han what I have now.