R9 390 is a very good card. But GTX 970 would be enough for you if you are playing in a regular single display monitor. But that PSU of yours seems a little bit unsuitable for a good gaming build. Corsair CS series PSUs are known to have low quality capacitors which tend to fail at heavy usage. I would say keep your GPU, change the PSU to a better quality one from Seasonic, XFX, EVGA or Antec.