Visual tearing on external display on a laptop

[Alex Deucher]

On Sun, Aug 3, 2008 at 11:27 PM, Jake Briggs <jakbri at coretech.co.nz> wrote:
> Hi All
>
> So I am having some issues with an external monitor (VGA-0) on a laptop.
> On the advice on someone from the #radeon irc channel, I tried to update
> the ati driver. I am running Ubuntu 8.04, the version of the ati module
> that ships with it is 6.8.0. The issue I was having - that the external
> monitor would not turn on - was solved by compiling and installing the
> ati driver version 6.9.0! Yay!
>
> But then I had some other issues. Basically there is some visual
> "tearing" I suppose, horizontal white lines that appear on the external
> monitor only, kinda like static kinda. This happens when moving windows
> around the desktop, and when playing video on the external monitor :(

Sounds like bandwidth issues.  Are you using an IGP chip?  Try
adjusting the DisplayPriority option in the device section of your
xorg.conf.  See the radeon man page for more information.

Alex