[lug] external monitor question

[Paul E Condon]

On 20111106_162930, Davide Del Vento wrote:
> Sorry for the follow up, but forget an important detail: the monitor
> is flat panel LCD and *not* CRT, so I was not expecting to see this
> behavior.
> Thanks,
> Davide
> 
> On Sun, Nov 6, 2011 at 14:19, Davide Del Vento
> <davide.del.vento at gmail.com> wrote:
> > Hi,
> > I'm trying to connect a Dell 19" monitor (bought in the USA) to an old
> > Dell inspiron 6400 Laptop (bought in Europe) with a VGA (analog)
> > cable. This is under Ubuntu 10.04
> > The laptop correctly sees the monitor and identify 1280x1024 as the
> > best setting, but on that setting the monitor display the image with
> > "waves" on the vertical axis. The monitor diagnostic also says that
> > this mode is a 58Hz or 59Hz signal (it does not always say the same).
> > The laptop thinks it's 60Hz.
> >
> > Playing with gtf and xrandr, I can modify the frequency (and maybe
> > even the intensity) of the waves from "very annoying" to "disturbing"
> > to "cool" to even "funny". But it never goes away (I haven't tried all
> > possibilities yet, though). On some modes (e.g. 63Hz) the monitor says
> > "Cannot display this video mode" which is strange since it can display
> > the 62 and 64Hz (by the way, the 64Hz are 64Hz for both the laptop and
> > the monitor).
> >
> > The question: do you think this is hopeless and I should give up
> > (given the 60hz vs 50Hz of the power line in Europe vs USA), or do you
> > think that I should eventually be able to find a non "waving" mode?
> > Ah, I also tried on laptop battery instead of power brick, FWIW.
> >
> > Thanks,
> > Davide
> >
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Older flat panel displays can have a goofy feature: 
They have in their software an implementation of the timing
requirements of a CRT monitor which is incompatible with the actual
hardware of the flatpanel display. I turn this off with the following 
/etc/X11/xorg.conf:

Section "Device"
        Identifier      "Configured Video Device"
        Option          "UseBIOS"       "off"
EndSection

This allows the modern X11 software to try timing parameters that
actually work, and fixes my problem. It may work for you. YMMV

-- 
Paul E Condon           
pecondon at mesanetworks.net