1440p 100hz Ultrawide stuck at 50hz (Displayport 1.2)

[Doctorgear63]

So I just received my new Samsung C34J79 Ultrawide. Looks all fancy and lovely etc. But on plugging it into my PC, in the monitor's settings it says the Recommended Resolution is 3440x1440 at 60hz, and in Windows it's stuck at 50hz.

The specs advertise this everywhere as a 100hz monitor. It's a Freesync monitor, but I don't know if this is related as others have said they have had it running at 100hz out-of-the-box, running Nvidia cards.
In the Nvidia Control Panel and in Windows Advanced Display Settings they both say it's running at 50hz, and I can't find anywhere to change this. I've tried running custom resolutions at 60hz and 100hz, but it's just totally unstable.

I'm running a GTX 1080 with up-to-date drivers, with a Displayport 1.2 cable, and according to the monitor's onboard menu it's running at DP 1.2. It's a cheapish cable though, I've got a Vesa Certified DP 1.4 cable on order, guess I'll see if that fixes anything when it arrives on Thursday. 

If anyone has any other ideas as to how I can get my 100hz, I'd greatly appreciate your input (Pun intended).

George

[Slottr]

I'd play around with the OSD settings before anything else

[Doctorgear63]

6 minutes ago, Slottr said:

I'd play around with the OSD settings before anything else

Can't seem to find anything related to changing the refresh rate in there though

[Doctorgear63]

New cable came, and now I can set it to 100Hz in the NCP so guess that was the issue. Now I know not to cheap out.