Well, have you tried (while connected to your HDTV: ~ # Xorg -configure ~ # X -config /root/xorg.conf.new If it works, copy the settings from the new xorg.conf to your current one. If your running Knoppix or Gentoo, you can always install ddcxinfo-knoppix to find out the HorizSync and VertRefresh. The sources may be available on the Knoppix site, but I run Gentoo so I can just: # emerge ddcxinfo-knoppix