I am running ubuntu amd64 version 8.10 on an ASUS motherboard with an integrated ATI HD 3200 GPU. I am running the ATI fglrx driver, and have connected the DVI output port to my Sony rear projection HDTV. The resulting image on my HDTV is larger than the screen, suggesting that I have an overscan problem. I tried disabling the TV overscan, but have discovered that the monitor that the driver is using is the tmds21, not the tv, and it seems that the TV overscan option has no effect on my image.
I have the same issue with my HDTV (connected with DVI-I->HDMI) detecting as tmds1. I discovered the default xorg.conf (the one ubuntu's install makes) + `aticonfig --initial` doesn't change a whole lot in xorg.conf.
However, if you run:
dpkg-reconfigure xserver-xorg
and then:
aticonfig --initial
It completely changes xorg.conf for the better - before I did this I couldn't even set my `aticonfig --resolution=#x#` because it thought I had no screen #0.