Benjamin Parsons :
DVI Output
2 (Dual-link DVI-I, Dual-link DVI-D)
Max Resolution: 2048x1536 @60 Hz.
HDMI-Output
1 (version 1.4a/2.0)
Max Resolution: 4096x2160 @24 Hz (1.4a), 3840x2160 @60 Hz (2.0)
DisplayPort
1 (version 1.2)
Max Resolution: 4096x2160 @60 Hz
But will i still get a solid 60fps with games like Planetside 2 and GTA V?
It should be able to run 1440p gaming fairly well in medium settings and possibly High. It will run 4k games but you may have to settle for Low settings to get decent/playable FPS. Two GTX 970's may get you to medium or High settings in 4k.
In Tom's GTX Titan review "Can a single GPU run 4k", it did it but the general consensus was not in High or Ultra settings. A GTX 970 would be good for 1440p. A GTX 980 would be even better.
I will be pushing a ROG Swift (1440p @ 144Hz) with my GTX 770 in the next couple weeks. I imagine I will be needing to upgrade to at least a GTX 970. I want the new 300 series AMD cards to launch before I make my purchases though so I can get a better deal.