Razer Core X, display port, 240hz?

Hey all, Wasn't sure if this was a razer, Nvidia or Samsung question so here goes: Setup: Samsung 27in 240hz (LC27RG50FQNXZA) Razer Stealth Early 2019 Razer Core X RTX 2080ti For some reason the displayport cable that came with my monitor doesn't seem to work with the core x. When I connect a hdmi cable from the core x to the monitor and when I connect displayport to usb-c they both work. I can only assume this is a faulty cable, unless someone believes otherwise? So I'm using the displayport to usb-c cable which I believe should support 240hz. When I go in to the Nvidia control panel I can only choose 120hz at 1080p. Anyone have any advice on troubleshooting this or maybe I am missing something or is it as simple as replacing the cable? Thanks, Andy