I'm not sure you'd be able to handle Arma 3 man but csgo will be fine. With those specs there's not too much benefit to getting 144hz unless you're only playing games like csgo or overwatch or something like that. Up to you though mate I mean either way 144hz is really smooth so your eyes will have a nicer time on windows. But really as long as you're getting over 60fps it'll be a big improvement. Personally I just upgraded my pc instead of worrying about monitors, I'd get a 144hz monitor but my 60hz works fine, no sense swapping out something that isn't broken.