4K 120 on XBOX Series X Works on the Q90R!! You must disable Freesync to work but it does work in Game Mode on port 4. If you get glitching then turn off Game Mode to be able to navigate through the XBOX menus to adjust between 120 and 60. PC mode not necessary, but still have to try it. Not sure if the current set up is 444 or not, but it works!!