Graphic Cards :: Display Port Gives No Signal

So I bought a new monitor, the MG279Q and tried plugging it in to my PC via displayport, the monitor comes with a DP->miniDP cable, (from GTX780 DP to monitors miniDP) and the monitor gives no signal. However the computer does recognize the monitor and for example gives the sound alarm for new device attached. I can also see the device describes as "Generic pnp monitor" and I can see it in the Windows's own control panel for monitor + the nvidia control panel (pics in the end). But it won't allow me to set the monitor to use..

I suspected that the cable might be broken so I tested it with my UX32LN (GeForce 840M) laptop which has a miniDP. I plugged it to the monitor (from laptops miniDP to monitors normal DP, the monitor has both DP and mDP) and wow, image straight away. So the cable should be fine I guess.. But this is somewhat of an different situation as I use different port in the monitor compared to my desktops GTX780. And I don't have other computers or gadgets that I could use to test the monitors miniDP port.

Next I plugged in the monitor via HDMI to my desktop and that worked just fine. It recognizes the monitor without problems. Using my old XL2411Z monitor with DVI + MG279Q with DP or the MG279Q with HDMI+DP at the same time I can see the MG279Q being connected twice but it only chooses the HDMI connection and doesn't let me change it to DP even though it shows the connection.

Here are some pics to explain it better:

Multiple panel settings window. It shows the MG279Q on the top (under GTX780 the one not clicked) but it won't let me click it to use. Sometimes it lets me tick it for a second but instantly ticks the box off. The monitor nro 2 is the MG279Q via HDMI.

Surround+PhysX window shows that I've connected the monitor via DP but it is greyed out. It also won't let me make a surround set with the Xl2411z + mg279q DP.

Changing resolution settings only displays the HDMI connected monitor.

So I tried uninstalling the Nvidia drivers + freshly installing them, did not work at all. Neither did uninstalling the generic pnp monitor so the computer would reinstall the displays drivers. I also freshly installed from Win7 Pro -> Win 10 Pro and no difference (was intended to do that later on anyway so I thought that I might check, my laptop is running Win10 and it's DP worked after all). I also went to BIOS and checked that iGPU is disabled + monitor setting is set to PCIE instead of auto, no use. I would also test the GTX780's DP on other desktop computer but I can't. Anyway I'm somewhat suspecting a software/hardware compatibility issue as the monitor is being recognized. Doubt the fact that the monitors miniDP or my graphics cards DP port is broken..

What should I do or try? I really want to run the monitor via DP so I can utilize the 144Hz refresh rate.

Tech specs:
PC: P8Z68-V PRO/GEN3 (bios v3202) + i7 2700K, GTX 780 DC2 (vbios 80.80.21.00.AS04), 4x4GB 1600Mhz DDR3, AX 760 PSU, Win10 Pro
Monitor(s): MG279Q + XL2411Z