P2715Q, Dual, 30Hz only on 2nd monitor?

Hi, I've just bought two dell p2715q's and have them up and running thjough a NVIDIA GeForce GTX 770 - 2GB. One using the supplied mDP to Digital port (4K at 60Mhz), the other using an HDMI to HDMI  (4K at 30Mhz) and I've also got a  small Wacom Cintiq using  the DVi port on the graphics card. My question is, is there any way of getting 60 Mhz on the HDMI Monitor, or is this the best I can get? (I don't think the graphics card has HDMI 2.0, though its difficult to find that info out.) I'm also shortly upgrading to a 8GB NVIDIA GEFORCE GTX 1070 Ti

(The only Caveat is that I'm a bit of a dunce when it comes to this stuff, I've looked on the internet, but don't really understand the information)

Many thanks 

P