KVM switch + Windows 7 creates monitor switching nightmare

You could test it by pressing the off button on one of your monitors. Does it resize the desktop?

Dunno. If the problem is only caused by the monitor info not passing through the KVM switch, I think it may. There may well be other issues too.

In my case it made it possible to use resolutions above 1600x1200, and refresh rates other than 60Hz, and the settings stick when rebooting or switching between computers.

Does this solution also address the problems reported in this thread in addition to the locked 60hz you experienced?

Hi all,

My story is similar to most others, got a noname KVM switch, old faithful CRT monitor, XP box that works just fine, and a W7 box that is stubbornly stuck at 60Hz. Googled for answers and found threads like this, but no solutions, just annoyed users like me and canned answers that were abrasive and useless.

After trying most everything with no success I found this doc about overriding EDID on MS site:

http://www.microsoft.com/whdc/device/display/edid_over.mspx

I wondered if it could possibly work if there is no EDID at all, tried it, and the bugger worked. I can now set the refresh rate and resolution as if the monitor is directly connected to the computer. Here's how to do it:

Run regedit, and go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY\Default_Monitor

This section contains settings for monitors with no EDID info. There may be one or more monitors listed there, possibly depending on how much juggling you've already done. Mine had two. If you are connected to multiple monitors, you may need to figure out which is which. The rest applies to a single monitor case.

The monitor keys look like random strings with numbers, "&" symbols and letters in them. Open one of them and select "Device Parameters". That key should contain a binary value called BAD_EDID.

Right click "Device Parameters", and add a new key called EDID_OVERRIDE.

Select EDID_OVERRIDE, and add a binary value called 0 (plain zero, no quotes). If the EDID you will be copying there contains more than 128 bytes (80 hex), you may also need to add binary values 1 to 5. See the doc for more info. It talks about an INF file, but it all amounts to adding stuff to the registry.

Now you need a copy of the monitor EDID. I got mine by connecting the monitor directly without the KVM switch, in my case it added a section at

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY\GSM4A4D

The name will vary depending on the monitor brand and model. That section contains settings similar to Default_Monitor, except under "Device Parameters" there is a binary value called EDID filled with valid data. Double click EDID, and copy the first 128 bytes to the 0 binary value you added. If the EDID is longer, repeat for the rest of the 128 byte chunks and use values 1 to 5.

Repeat the procedure for all monitors at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY\Default_Monitor, close regedit, reboot, and presto, the 60Hz lock should be history.

Emre, 

Thanks for the info.  I am using driver version 186.27 (latest Windows update driver without installing direct from nVidia) and it is doing what you want on my setup (I can turn my monitors off and on without any change to my desktop).  You may want to try the Windows update driver version.  I will try the latest nVidia drivers again to see if there is a change for me.

I have read and do understand this thread.  I think whatever the fix is, it should be a controllable fix.  My scenario is this: Projector is monitor 1 and external LCD is monitor 2.  I have my settings to "desktop only on 1".  Previously in Build 7100, whenever I turned off the projector, Windows 7 would treat the projector as disconnected and automatically move my desktop to the external LCD... quite seamlessly I might add.  Now I have to change settings prior to turning off my projector in order to keep using the computer.

I'm under the impression that each monitor should have a choice for how it is treated when disconnected.  Users of KVMs should be able to turn this "auto-desktop" feature off.  Users who want the ability to specifically turn off their monitor or have monitors that do not transmit EDID data in standby mode should also be able to turn the feature off.  Users who want their desktop to automatically resize should have the ability to use this auto-desktop "feature" (specifically laptop users).

Again, I want the problem you have and you want the problem I have.  Lets swap monitors.

-Chris