xr280xr wrote:
> After re-installing here is some more behavior that might narrow it down. I'm
> pretty sure something is different about this Dell monitor. It acts like it's
> not plug and play or not multi-display friendly or something.
>
> I've been using my computer with only the Asus mointor pluged in to the
> nvidia quadro card and it has worked fine. Quadro card has two DVI out puts.
> I notice if I unplug the Asus monitor and plug it back in, I hear the XP plug
> and play device found sound. I tried switching between the two DVI plugs and
> it works fine on both.
>
> Next I tried plugging in the Dell again. It doesn't play the plug and play
> sound effect for this monitor and doesn't send it any signal. If I go to my
> display settings, it only recognizes 1 monitor: (Default Monitor) on NVIDIA
> Quadro FX 570. When checking the display settings in the nvidia control
> panel, it shows a single monitor and actually shows the name: Asus VH236H.
>
> Here's the stranger part. If I go to Device Manager>Monitors>Scan for
> hardware changes, then the sound plays and Dell E1909W(Digital) shows up in
> the list of monitors. When I return to the windows display settings tab, it
> still only recognizes the 1 monitor. Strangely, when checking the nvidia
> control panel settings, it now shows only Dell E1909W and no longer sees the
> Asus monitor. What seems like the biggest clue in all of this is, if at this
> point I unplug the Dell monitor, the plug and play noise plays as if it just
> found the Asus monitor again even though it was already plugged in. Once I
> crawl back out from under my desk (which is getting really fun 
Asus VH236H
> now appears in the still open nvidia control panel settings screen.
>
> So it's like the Dell monitor is not plug and play, and once it's
> recognized, it wants to be the only display. I need an expert! Thanks.
>
You can review the Plug and Play coming from the monitors with this.
If you can see the two monitors in the pull-down menu, and both
displays gobs of numbers, then chances are both monitors are doing
their jobs. If one display shows and the other does not, there could
be some kind of conflict (or bad implementation) on the video card.
http://www.entechtaiwan.com/util/moninfo.shtm
Page 8 here, shows a hardware block diagram. You have to be very patient,
as when you use Adobe Acrobat Reader to view page 8, it can take many
seconds before the diagram appears (on my slow computers, I have to wait
30 seconds before the diagram appears). So flip to page 8 and wait until
a yellow colored block diagram appears in the middle of the page.
http://ati.amd.com/products/radeonx1k/whitepapers/X1000_Family_Technology_Overview_Whitepaper.pdf
The concept there, is there are logically two display channels on the
video card. A display channel is "bound" to a monitor at some point.
A video card may have three connectors on the faceplate, but only
two of them can be driven at any one time, as there are only
two logical display channels in a multi-head capable desktop video card.
(Cards capable of driving four monitors, are cheating, as they use
two GPU chips, and really, it is the same ratio of two display channels
available per GPU chip.)
Now, consider your scenario. You have two monitors. Only one of them
seems to "bind" to anything, and the monitor that wins seems to be
random.
Imagine, for some reason, that only one logical display channel was working.
This could be a driver issue (such as the driver not installing properly),
or some other kind of interference, such as running in SLI mode.
Would the second card also be an FX 570 ? Did the Nvidia driver
assume they're operating SLI, and do some kind of bus-based
SLI combining of the two cards performance ? Perhaps that
results in one logical display channel, and only the ability
to drive one monitor. (Two cards in SLI, as far as I know,
are still limited to driving one display. Maybe that has changed
recently, but I don't have an easy way to check that.)
Now, on my computer, I've got it easy. In Device Manager, each
display channel of my video card, has its own entry. In other
words, I have one video card installed, but there are two
entries in Device Manager. I can tell by looking at that, that
logically all is well.
It seems for more recent video cards (mine is ancient), that
has changed. They no longer necessarily put multiple entries
in Device Manager. I was hoping to use that as a debugging tool,
but looking at pictures of Device Manager on the web, they
don't seem to use that concept any more. Now, they seem to
put only one entry per video card. That leaves me with
no simple way to verify both logical display channels are available.
Paul