You have an awfully old CPU and mobo for a system with a 970 gtx...
To power this should not take much more than 500w tops. So to be safe opt for a Seasonic, Superflower, Silverstone, Enermax or EVGA PSU with around 600w to be on the safe side.
I recommedn upgrading the cpu and mobo sometime, so as not to experience bad performance from your modern GFX card.