@apsturk
During the installation I gave maximum resolution in os4.x of 1920x1200. After reboot changed to automatic dectection of settings in the Monitors tab in screenmode prefs. After that al resolutions are shown. I'm using a Dvi-d single link to HDMI cable to display 1080p, 2560x1440@60 and 3840x2160@30 with a Radeon 6450 card.
