I just bought a CAC-1085 and it will only display 4K60hz, i've tried a few different version of Nvidias display driver but the best I can get is 4K60hz RBG 10bit color
Which drivers did you try?
There are more reports on the forum that the latest drivers of Nvidia broke the 4K120Hz again,
Have you tried these drivers?
https://www.nvidia.co.uk/download/driverResults.aspx/180642/en-uk
Make sure to DDU your current drivers first!
https://www.guru3d.com/files-details/display-driver-uninstaller-download.html