I have an Acer XB241YU capable of 165hz on overclock with Display Port. I have been able to do this for almost a year now, all of a sudden, my NVIDIA control panel only goes up to 85hz. I've tried unplugging everything, even my GPU (1080ti The Duke). Custom resolutions don't work. I have the latest drivers. My Display Port cord is fine (worked yesterday). I don't know what to do please help.