The GTX 650SC is a decent card for DayZ Epoch. My brother's PC runs a GTX 560 which has similar performance to your card, so expect to run at medium-ish settings.
Remember this game isn't a very well multi-threaded game, nor is it SLI or Crossfire optimised. The game does have profiles for SLI & crossfire but isn't very good at running them, so if you plan on ever getting SLI or Crossfire capable graphics cards for this game, you're gonna have a bad time.
This game will only utilise 1 CPU core of your 4 available CPU cores and will either consume 1 entire CPU core or divide the load across all 4. I am unaware of your CPU however you should still have no problem running this game on decent settings whilst receiving 40+ frames, which in this game is perfectly acceptable.