After some research, looks like this monitor is the one that suits me. Acer Predator XB271HUA 27" WQHD Nvidia G-SYNC Gaming Monitor , 2560X1440 , 1MS , 165Hz Max , USB 3.0 HUB ,

However it warns that a connector needs to be

One area where the XB271HU falls behind, however, is connectivity. Thanks to the limitations of Nvidia’s G-Sync image processor, this display has only two inputs: one DisplayPort and one HDMI. The former supports fast refresh rates and G-Sync, while the latter will allow up to 2,560 x 1,440 resolution at 60Hz.

I have had a search for DisplayPort connectors but not sure what they actually are.

At the moment my new PC has only a HDMI port using HMDI in on my old PC monitor.

Does that mean i need to buy a HDMI to Displayport connector and if so where would i purchase one?

Please and Thank you.