If it's going to be something along the lines of War Thunder or Team Fortress, something like a GT 740 or a GTX 760 will do. Right now, if all you're going to play is around that intensive, you don't need anything more expensive than an i3 or an i5. I'm still running along with a Core 2 Duo and a GTX 760 I added not too long ago.
If it's something like Battlefield 4, then you'll need something with the power of a stronger i5 or an i7. GPU wise, a 7 series will fit the bill for 2 or 3 years.
