[CLUE-Tech] laptops and X

[marcus hall]

On Sat, Jun 26, 2004 at 08:16:02PM -0600, Jeff Cann wrote:
> ... I tried it and when I booted with external monitor, a utility came 
> up and reported that X could not be started.  I unplugged the external 
> monitor - no changes to the XF86Config -- restarted X and it worked.
> 
> So something appears to detect my external monitor.
> 
> Note that if I boot in 1024x768 w/o monitor and then plug into monitor, it 
> displays properly.  It only switches to 800x600 when the external monitor is 
> plugged in on boot.
> 
> weird.

There is a standard called DDC (Display Data Channel) that allows a
video card to detect an attached monitor's resolution, scan rate, etc.
It is entirely possible that X is getting this info from the monitor
and determining that it cannot support 1024x768.  Since you have
removed the 800x600 setting, it no longer can find any scan rate that
the monitor will support.

There is an option "NoDDC" that can be set for most video cards.  Perhaps
this is what is tripping things up?

You can try this by adding in the "Device" section:

	Option "NoDDC" "true"

(You may also try it in the "Monitor" section -- I have seen it there as
well).

HTH

Marcus Hall
marcus at tuells.org