Windows 7 Dual Monitors - Only One Works at a Time

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SpiderKnives

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Hello,
I've recently switched from Windows Vista to Windows 7 x64. I use the word switched instead of upgraded because I formatted my old drive instead of installing over Vista.

I have been using two screens for forever now, both LG Flatron L1750HQ, both are digital and have served me well. My graphics card is an NVIDIA GeForce 8800 GTS, which has two digital outputs. I have the latest NVIDIA drivers, and I have the drivers for my screens (though they are old, June 2007, and I can't find any newer ones... which might imply an EDID problem? Dunno). I have also run every Windows 7 update known to man.

To describe the problem: only one of them ever works at a time (which implies the screens themselves are okay), and both outputs work as well. To top that, Win 7 does recognize I have a dual display, but one is always in digital power-saving mode (no signal, I guess).

When my computer boots up, the left screen shows the boot process, while the right one has no signal. When Win 7 boots, its the other way around.

In the NVIDIA -and- the Win 7 control panels both screens are visible, shown side by side, and set up properly with and without the screens' driver, but that does nothing to solve the problem.

I've also examined my BIOS, but I doubt its anything to do with that since I haven't touched my BIOS in ages and it worked just fine on Vista. I'd wager that if I go ahead and install Kubuntu on this machine, I'll get my dual screens back, but I don't want Kubuntu.

Thanks in advance for any assist
 
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np

I have a Primary monitor @1920x1200 and a secondary @1280x1024.

What do u have?
 
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Video Card: GeForce 8400 GS
Card Output: DMS-59 to 2 VGA adapter; I've tried two different adapter cables. DMS-59 provides two DVI or VGA outputs in a single connector with the ability to support two high resolution displays.
Latest Driver: 306.23 - installed a clean reset install of the latest Nvidia driver released last week.
Same Resolution: 2 of the 4 monitors I have tried have the exact same 'recommended' resolution (1280X 1024), both 60Hz, and I chose 16 bit color for both instead of 32 to reduce resources.

Ubuntu worked: Dual display worked immediately when I tried it in Ubuntu. So, it's not the hardware. It works in Ubuntu 12 too but not properly -it won't transfer windows across screens.
In Windows 7, the monitor on cable 1 displays during startup then powers off at login at the same time that monitor 2 powers on. Windows 7 behaves as though dual display is working even though the only time monitor 1 displays is on startup. For a single display, only cable 2 can be used as well.

Both 'Extend these displays' in Windows Screen Resolution and 'Extend' in the Nvidia Control Panel is selected. And changing which one is primary does not turn on monitor 1. Nor does switching the position of display 1 in either (ex. left/right/top/bottom).
 
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k

sounds like u have covered a lot. i think it's np with ur understanding to try something not so simple for diagnostic purposes. But be careful and read closely.

See, just to check it out, let's try checking device manager for ghost (hidden) drivers. (it was easy before vista and Win7 but now it is a little complicated.) And it use to always help performance and solve driver installation stuff; because of the old way that IRQs used to be assigned by Windows. But nowadays it's just part of diagnosing things. Only Sometimes does it matter. But do it anyways. But carefully. We're just researching.

(Read closely.)
1. Open a Command Prompt by going to Start>Run and typing "cmd" (without quotes). (For Win7 just type “cmd” into the startmenu and hit Enter.) Once the MS DOS prompt is open, type the following lines, pressing Enter after each:

Set devmgr_show_nonpresent_devices=1
Devmgmt.msc

Note, you can type "exit" (without quotes) in the MS DOS prompt window to close it at any time after this.

2. In the Device Manager window that opens, go to the View menu and select 'Show Hidden Devices' - this is very important if you want to see the unused devices. Now expand each of your devices and look through all the sub-components listed. You will see that some of the devices are shown in a lighter grey color.

3. For the purposes of this guide, what we need to look for are entries under the Monitor and Display Adapter devices. Under Monitor there should be one darker monitor entry for each monitor on your system. If there are any greyed out entries, you can remove them by right-clicking on the entry and selecting 'Uninstall'. Do this for all greyed out entries under the Monitor device.

4. Under the Display Adapter device, if you find two entries - a main one, and another one which has 'Secondary' next to it - these just indicate that your graphics card is capable of two separate outputs to two different display devices. You should keep both of these. Do not attempt to uninstall the dark entries under here. You can however uninstall all other greyed out entries under the Display Adapter device list, especially those which relate to previous graphics cards you have had on this system.

5. If you're feeling game, you can go through some of your other device entries and delete grayed out devices which you know for certain are no longer connected to your machine, or are traces of a device which has been moved around a few times. For example, under Human Interface Devices you may find multiple grayed out entries for a mouse which you may have moved from one port to another. As long as there is a solid entry for the device when it is still connected to your system, you can uninstall the grayed out ones.

6. A final word of warning - I do not recommend uninstalling devices which you are not sure about. Most importantly, do not uninstall any grayed out Microsoft (or other Codec) entries under the Sound, Video and Game Controller device, and be extremely careful about entries under the Non Plug and Play Drivers, and Network Adapters device list. If in doubt, do not uninstall a device.
If you do happen to uninstall a device which is still connected to your system, it's not the end of the world. Windows XP and Win7 will usually re-detect it upon reboot and look for drivers to reinstall it. However I urge you to take caution with the above procedures and only do Steps 1 - 4 above if you have any doubts.

Credit for the above goes to: Link Removed

Let me know wat u find, nikpapag, and we'll cover properly uninstalling drivers and reinstalling them. GL
 
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Wow, that seemed like a good thing to check. But, it looks like nothing extra is in the 'Display Adapter' and 'Monitors' sections.
 
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nikpapag said:
View attachment 21239Screenshot
Click to expand...

cool. that helps.

ur DM looks just fine and there's no reason to believe anything funky is going on.

Q: Have right clicked on Monitor 1 and selected, "Make Primary"?
(sry i had to ask.lol)

Nikpapag, there use to be a difference between using the inner (left side when facing the back of ur PC) or outer (right side) port. There still may be a difference. (Windows/nvidia driver-wise. Ubuntu is too smart to mess up. )

Therefore,

01. Try shutting down PC.
02. Then disconnect the monitor you have plugged into the inner (left) port.
03. Start PC and get the single monitor (plugged into the right port) configured with proper resolutions.
04. Restart and make sure the single monitor is still working fine.
05. Shutdown again, and plugin another monitor into the inner (left) port. Start PC and see if you can enable the 2nd monitor.

If this fails let me know.

GL
 
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Yes, choosing primary as either 1 or 2 does not turn on 1. Nor does switching the position of display 1 in either control panel left or right or top or bottom.

Well both cables are split from the DMS-59 (DVI) to 2 VGA. The left inner one (facing the back) is marked as 1 and the right outer one is marked as 2 on the splitter cable. I have tried before what you said starting with one on cable 2 then adding the other on cable 1.
 
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you don't mean that there's only one single DVI cable plugged into the vid card and that that cable splits into two VGA connectors card do u?
 
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A DMS-59 provides two DVI or VGA outputs in a single connector with the ability to support two high resolution displays.

There is a right outside port; but it's an S-video.
 
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nikpapag said:
A DMS-59 provides two DVI or VGA outputs in a single connector with the ability to support two high resolution displays.

There is a right outside port; but it's an S-video.
Click to expand...

nikpapag - I don't have the answer for you unfortunately but I have the same problem on an almost identical setup. My HP dc7800 PC was running Vista with two Geforce 8400GS driving four monitors (via a DMS-59 socket on each of the cards).

I put in a new SSD on which I installed a fresh copy of Windows 7 64-bit. Screen 1 displays at boot but then flicks to Screens 2 & 4 once Windows boots. The nvidia control panel shows four screens but there is no output on Screens 1 & 3. All four screens are the same make and model.

I spent a day installing and uninstalling drivers, shifting the cards into different sockets and back to no avail and ended up putting the old HD back in (back to Vista) and everything worked fine.

I was wondering whether it is something to do with DMS-59 as this connector seems relatively uncommon but I haven't been able to find anything suggesting they need particular drivers installed.

Good luck - I hope you find a solution and if you do I'd be really grateful if you could share it
 
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Dual display monitor 1 loses signal after startup; Linux displays both

Windows 7 64 turns off the monitor 1 signal after startup. At login, it powers off monitor 1 and powers on monitor 2. Windows 7 behaves as though dual display is working even though monitor 1 does not display. It's the same for single display, the monitor will not work on cable 1 except at startup.

Both 'Extend these displays' in Windows Screen Resolution and 'Extend' in the Nvidia Control Panel is selected. And changing which one is primary does not turn on monitor 1. Nor does switching the position of display 1 in either (ex. left/right/top/bottom).

GeForce 8400 GS; Dual Monitor Solution 59 pin socket (DMS-59) to 2 VGA adapter -tried two of these adapter cables.
Latest Driver: 306.23 - installed a clean reset install of the latest Nvidia driver released last week.
Same Resolution: 2 of the 4 monitors I have tried have the exact same 'recommended' resolution (1280X 1024), both 60Hz, and even chose 16 bit color for both instead of 32 to reduce resources.

Linux worked: Dual display worked immediately when I tried it in Ubuntu 10. So, it's not the hardware. It works in Ubuntu 12 too but not properly -it won't transfer windows across displays.
My Windows 7 64 is an upgrade from Vista 64. One person in another forum with the same problem resolved theirs by reinstalling Windows 7. But another got the same problem only after a fresh clean install of Windows 7 64 with the same GeForce 8400 GS and DMS-59 when it had previously worked in Vista. Link Removed

Pushing a menu button on monitor 1 does wake it up, but just says,
1: Analog Input in Power Save Mode
Press Any Key on Keyboard or Move Mouse
 
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I don't know what you mean 'only in Linux is it going to show in Extended view'. Extended View is selected in both the 'Windows Screen Resolution' and the 'Nvidia Control Panel''.

And I can see by using Monitor 2 that Windows is operating in Extended View.
 
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Nvidia driver 285.62 from Oct 2011 is the latest driver to dual display. And all previous drivers back to 185.93 from May 2009 work as well. Also beta 290.53 works.

But 295.73 from Feb 2012 and later will not dual display.
 
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I'm sure it doesnt help because it's like 6 years late lmao but I had the same issue oddly enough It was my cables being different kinds until I made them both the same cable it wouldnt work
 
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