KVM switch + Windows 7 creates monitor switching nightmare

Here are some more observations from my configuration. I'm beginning to think the disconnected-connected problem has nothing to do with EDID.

My monitor has a VGA cable and is connected to the video card with a DVI to VGA adapter. If I unplug just the VGA cable, regardless of going through the KVM switch or not and regardless of the EDID override, I don't hear the disconnected-connected sound. Only if I unplug/replug both the cable and the adapter at the same time I get the sounds. Again the KVM switch or the override do not make any difference, so that would indicate the "connected" status is not based on the EDID.

If I first unplug just the VGA cable, and then the adapter, I get the disconnected sound, but if I then replug just the adapter, and then the VGA cable I don't get any sound at all. The DVI to VGA adapter has the hot plug pin 16 permanently wired to the +5V pin 14, so the hot plug pin is definitely involved.

I did some googling and found comments that indicate the connected status is determined by the hot plug pin, and detecting load on the signal pins, not the EDID. That would explain why I consistently get the connected-disconnected sound only if the unplug/replug both the adapter and the cable at the same time, regardless of the EDID-stripping KVM.

So, perhaps some monitors are making the inputs temporarily float when you turn on the power. If you are then using a DVI cable, the combination could make the overly anxious W7 think the monitor is temporarily unplugged. I have no idea what could possibly make it happen if the monitor is already on. In any case, using a VGA cable might help as a workaround since the DVI to VGA adapter makes sure the hot plug pin is always "hot".

Unlike some here, I have no problem if I come across as a microshaft hater.  Use Linux.  It works.

Already using Linux. That's not the problem here. Your answer was not helpful. But Microsofts answer wasn't helpful either.

Btw, why don't I get a cursor while typing here? Extremely annoying.

Unlike some here, I have no problem if I come across as a microshaft hater.  Use Linux.  It works.  Fornicate you microsoft!

Good advice! I can come up with some more: Take your bicycle and go for a ride. Take on your skates and go skating on one of the lake around you (at least this one currently works here in Sweden). Use your DVD player and watch a good movie. All these advices will work. And similar to your advice they totally misses the point.

The point is that I, and several other people in this forum, have things we need or want to do with our computers. And the tasks can't be performed unless we use at least two computers, where at least one has Windows7 installed, a KVM-switch we already own and one screen.

My setup is

• One older computer with Windows XP where I have my scanners connected, one slide scanner and one film scanners (no drivers on GNU/Linux). Simple graphic card with VGA connector.
• One newer computer with Windows 7, 64bit, and my main applications, Adobe Photoshop Elements and Pinnacle Studio video editing (choice of applications are not negotiable). NVIDIA GeForce 8800 graphics with two DVI connectors and VGA to DVI adapter.
• One 21" CRT, Gateway, with VGA connector
• One KVM switch for VGA.

The setup worked prior to upgrading the newer computer from Windows XP to Windows 7.

My problem is that whenever I switch computer with the switch Windows 7 forgets on what connector on the graphic card the KVM is connected and the picture disappears and doesn't come back again.

The requirement for an useful solution is that it will enable me (and all other posters with similar equipment) to use our current equipment with Windows 7. Any solution that contains, switch KVM, switch operating system, or similar is not useful.

The reason I believe I can push this requirement quite hard is that the root of the problem is a stupid design decision that added a feature (continually checking the monitor) that doesn't give any benefit to the user.

And by the way, diemsdie, I'm not a GNU/Linux hater. I'm using it for software development at work, but I believe in the right tool for the job.

I was actually testing similar things this weekend as Xenubite.  To reiterate, my problem is my desktop is never auto-resized, and I want it to be (so once I understand what is unique about my setup, that information should be useful to almost everyone else).

HDMI 1.2 specification states "An HDMI Sink shall not assert high voltage level on its Hot Plug Detect pin when the E-EDID is not available for reading... The Hot Plug Detect pin may be asserted only when the +5V Power line from the Source is detected".  It also states "Note that many Sink devices simply connect the HPD signal to the +5V Power signal through a 1000 ohm resistor" and "An HDMI Sink shall indicate any change to the contents of the E-EDID by driving a low voltage

level on the Hot Plug Detect pin for at least 100 msec" [1].

My computer only considers my projector disconnected when the “Hot Plug Detect” (HPD) line is disconnected.  Further, the projector can be in standby or disconnected from power but connected via HDMI cable and Windows 7 will still use it for my desktop.  I checked and it just uses a 1000 ohm resistor from +5V pin to HPD pin.  I am not yet sure whether the +5V pin actually ends up powering the EDID ROM.  Assuming it does not (and a software solution is not provided), one possible hardware work-around may be to make adapters that break the HPD line and connect a 1k ohm resistor from +5V to HPD on the source side to prevent the HPD pin from ever being driven low.  Installing one at each Windows 7 monitor prior to a KVM should stop the resizing.

Xenubite, I expect that is what your DVI -> VGA connector does.  Can you check resistance from pin 14 to pin 16 on your DVI adapter?

I would much rather see this problem resolved in the software.  It is absolutely possible, I just do not know if it will ever be done.

-Chris

[1] http://www.hdmi.org/download/HDMI\_Specification\_1.2.pdf