Dr. Nikolaus Klepp wrote:

> Usually it's selfconfigured, but you could check if /etc/X11/xorg.conf or
> /etc/X11/xorg.conf.d exist. If yes, it might be a good idea to delete
> these and try again. If they don't exist, you'll have to ask the
> searchengine of your trust (sorry, don't have any ATI GPU here)

AMD discontinued support for older cards and firmware might not work is what
I know. I experienced this on one ubuntu, but might be something else -
worth checking.