I've got an AMD graphics card (6900 series) and just installed the beta driver (after fighting with the stable one). I'm also using a screen with 2560x1440 resolution connected via HDMI which works fine on Windows (so I assume there is nothing wrong with the screen itself) but not on Ubuntu. The maximum resolution I can select is 1920x1080 which looks ugly.
However, I can use 2560x1440 with DVI but I use the built in speakers via HDMI so I'd like to keep that.
I've tried to use xrandr to basically fake it but xrandr can't find a HDMI output I could add the new mode to.
My OS is freshly installed except for the driver.