So i am making a build and i'm wanting to put a MSI R7 260X OC 2gb GDDR5 VRAM in it and my CPU would be a AMD Phenom II x6 1055t. It's my first build and i just want to make sure that i can get top performance. Thanks in advance.
Definitely. If you can have a 600W PSU, you can have a bit of a headroom for future upgrades. But 500W is well enough for your current specification with an R7 260X.
I even had a 500W Plus 80 Silverstone used for my old R9 270X