Strange video troubles (DPMS & nv driver)

[cothrige <cothrige@bellsouth.net>]

I have been having a couple of odd developments lately which I think may
be traceable to my Samsung SyncMaster 940BW 19" LCD monitor.  It started
when I noticed I was not getting consistent reactions to my DPMS
settings.  In my xorg.conf I have the following:

Section "ServerFlags"
    Option         "BlankTime" "10"
    Option         "StandbyTime" "40"
    Option         "SuspendTime" "50"
    Option         "OffTime" "60"
EndSection

...

Section "Monitor"
    Identifier     "940BW"
    HorizSync       30.0 - 81.0
    VertRefresh     56.0 - 75.0
    Option         "DPMS"
EndSection

I would expect that after 10 minutes idle my screen would blank, and
then after 40 it would enter standby mode, and so on.  However,
sometimes it just never does any blanking or sleeping at all.  Other
times it will blank and then never sleep.  Of course, often it does both
just as it should.  I have tried using xscreensaver, which I don't
usually run, with its power management settings, but it didn't seem to
affect anything.  There is just no telling really what may or may not
happen in this area.

In response I have tried to find something in the logs regarding actual
calls to the monitor relevant to DPMS, but have found nothing.  Is there
a way to see when the computer sends a signal to the monitor to blank or
sleep and see how the message was received or responded to?

In trying to solve this problem I thought I would make sure it was not
video driver related and tried the nv driver.  I usually use the nvidia
driver.  However, I could not get nv to work.  Everything was a bit
fuzzy, and my fonts were all jaggy and hard to read, with the vertical
lines being very faint.  Also the screen was too tall for the monitor by
about thirty pixels, and was way off to the side with about two inches
of black down the right.  This could not be corrected with the
horizontal placement setting, and the best I could get was about a half
inch of black on the side, with the other side cut off.  Obviously it
was completely unusable.

I can think of no reason why the nv driver would fail this badly, and
why DPMS is so hit and miss.  Perhaps it is as simple as a bad monitor,
or maybe it is two unrelated coincidences.  I would like to make sure
before replacing it but just can't find much information to make a
judgement by.  Has anyone heard of something like this with 'nv' or have
any suggestions about tracking down DPMS and what is going on there?

Many thanks,

Patrick