You won't need a new power supply. You need a new motherboard because your older one is for AMD CPU socket.
I recommend Intel Core-i5 4570 Haswell 3.2 GHz CPU and GTX 750 Ti. Similar prices but newer devices and better performance. You can average 40 FPS at ultra on 1080p on AC4 with that GPU and CPU combo.
alright, but can you tell me what games can i run and on what settings,