CPU is good but RAM is small for GTA 5 and FIFA 15 you are able to play on LOW settings every things is low.
my rig is CORE I5 3.30ghz and 8gb ram and gt 730 2gb ddr5, i got 25 fps on med settings in GTA 5 with this my desktop configuration example you got your answer that how much fps you gain from your configuration.
can you please update the fps while you play GTA5 in your PC that how much you get FPS (for my general/knowledge purpose)