Not sure, what kind of games are you looking forward to play, and what settings will you want to play on, if you don't mind graphics that much, I would say that your computer is "OK" for Medium-High settings depending on which game are you going for.. but if you are going straight to heavy gaming in which both are CPU or GPU intensive and have a little bit more to spare, I would pick a I5 7400 or any I5 at least, a I3 Dual Core for heavy gaming won't be much beneficial. As for the GPU I would definetely pick a GTX 1070. As for the PSU, I advise you to pick a 550W if you are planning on upgrading your rig in the future.
But that will all depend on your budget as well.
Cheers.