KVM switch + Windows 7 creates monitor switching nightmare

I think I've found a solution!  My KVM/dual monitor setup was working just fine for over a year, and all of a sudden I started having this issue.  The solution that worked for me:

 

-Show all ghosted and disconnected devices in devicemanager per http://support.microsoft.com/kb/315539

-Uninstall all monitors

-Reboot

 

After Windows came up and detected my monitors, my KVM setup worked perfectly.  Yay!

OMG YOU ARE MY HERO

well it worked once but as soon as I use the kvm a second time it does the same thing. I did notice that telling device manager to look for new hardward finds the other monitor again.

I think I've found a solution!  My KVM/dual monitor setup was working just fine for over a year, and all of a sudden I started having this issue.  The solution that worked for me:

 

-Show all ghosted and disconnected devices in devicemanager per http://support.microsoft.com/kb/315539

-Uninstall all monitors

-Reboot

 

After Windows came up and detected my monitors, my KVM setup worked perfectly.  Yay!

OMG YOU ARE MY HERO

I think I've found a solution!  My KVM/dual monitor setup was working just fine for over a year, and all of a sudden I started having this issue.  The solution that worked for me:

-Show all ghosted and disconnected devices in devicemanager per http://support.microsoft.com/kb/315539

-Uninstall all monitors

-Reboot

After Windows came up and detected my monitors, my KVM setup worked perfectly.  Yay!

I'm trying to get to the bottom of this issue but I'm seeing two destinct symptoms here:

[...]

Thanks,

-Richard P.

My issue is much simpler than the two you've identified:

I have a Windows XP SP machine and a KVM switch, both corporately owned and managed, so I can't change the OS  to Win 7 or plug in new hardware.   When the monitor is plugged directly into the VGA port of the video card, Windows detects a PnP monitor and correctly sets the resolution to 1440x900.  When the monitor is plugged into the KVM, the EDID is blocked and Windows detects a Default Monitor, and the resolutions available on the slider range from 800x600 up to 2048x1536, but do not include any widescreen formats like 1440x900 or 1680x1050.

Johnnyxz nailed what we want back in November 2009:

Please give us the option to turn the automatic screen resolution change-thing off.

If the user checks a box to "Lock Resolution", the slider should offer *all* resolutions, the user sets the slider to what he wants and hits "Apply", and the video card goes to that resolution and stays there regardless of what monitor is plugged in.

That seems like a simple enough request that doesn't require debugging various models of video cards, KVM switches, OS versions and patch levels, etc.

I think i found the solution. You must indicate to the video driver to not detect the EDID information and to force it.

There is a registry key in nvidia driver named : OverrideEDIDflags.  You have to create it to force the edid information

First, you have to find your 4 digits EDID information : You may use a little program named Phoenix EDID designer (Google is your friend). select your EDID corresponding to your monitor and click on Binary viewer. The 4 digits are the 8 to 11 digits in this binary list. For example, the LG E2240S, it's 1E 6D A3 57.

Then you have to go to registry in : HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video and found the guid corresponding to your Nvidia card. Look the information inside keys. You should find yours easily.

For me it's : HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video{C3139BD6-51C6-4EE9-93C3-BA425FA829F4}\0000

add the binary value key under 0000 : OverrideEDIDflags

and write your 4 digits and 00 00 FF FF 04 00 00 00 7E 01 00

So it gives : 1E 6D A3 57 00 00 FF FF 04 00 00 00 7E 01 00

Reboot your pc and it works !!! Well, it works for me...

Francky

• 1 PC with Win7 x64
• 1 PC with XP
• 1 KVM Trendnet TK-209
• 1 HD Monitor LG E2240S