I recently purchased a QNIX Q2710 27" 1440p monitor and my current GTX 660 is really, really struggling. I am able to just about play BF4 at this resolution but only if I drop all my settings or almost all of them to "Low" and I'm still not as competitive as when I'm playing at 1080p.
BF4 is still in beta so performance issues are expected since it still isn't optimized. This is so even if you use the beta drivers. Gtx 660 won't max a lot of games at 1080p. That's just the fact.
For 1440p, I would suggest a gtx 780 or an r9 290x (based on benchmarks I've seen)