P55-US3L - Erroneous double-entry of specific devices in Device Manager

[forumjoe]

DM et al,

I've solved the mystery of my monitor double-listing. It's not been due to the way I installed the monitor but is, in fact, down to a valid feature of the Matrox graphics card that I use.
 
The card is dual-DVI, ie. if required, it can drive two monitors simultaneously at a specified resolution. I happen to be using just one of the DVI outputs on the card, so there's a cable connection to the monitor on that particular output but nothing attached to the other output. Matrox have told me that, with cards having dual-outputs, it's possible that Device Manager will show the outputs as either 'PnP Monitor' (plug n' play) or 'Default Monitor', or a combination of the two. All monitors actually connected to the card are detected and displayed by Windows as 'PnP Monitor'. If no monitor is connected to an active output on the card, or a monitor simply isn't detected, it's listed as 'Default Monitor' (or sometimes 'Unknown Monitor'). As soon as a monitor is connected to an active output, it's seen as 'PnP Monitor'. Then, once the INF driver of the monitor is also installed, 'PnP Monitor' changes to the actual name of the monitor.
 
So, in fact, there's nothing wrong at present with the listing I have in Device Manager. It's correct.

[Dark Mantis]

Hi

So it was correct after all then. That's what I thought but I must admit you described the why much better. It is now easy for everyone to comprehend why it shows as it does.

[forumjoe]

Yes, I'm pleased that the monitors mystery didn't turn out to be an installation problem or anything to do with the motherboard.

I guess there are relatively few people using two monitors or more these days off the one graphics card. Also, most people will, I suspect, have just one DVI output on their graphics card (although perhaps having other different types of outputs). So, this finding won't hold any significance to them. However, for those who happen to have two DVI outputs that can be run simultaneously and who may be puzzled when they see two listings in Windows when they happen to be using just one monitor, I trust that my explanation will put their minds at rest.