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Windows 7: KVM switch problem

31 Oct 2009   #1

Windows 7
KVM switch problem

I have a relatively expensive DVI KVM switch which now only partially functions since Win 7 installation.

It switches to the other machine fine, but when I return from the other machine (XP) to my Win 7 machine, the monitor remains blank. Everything else works, but I have to disconnect the monitor from the KVM and reconnect it in order to get video back.

KVM is Star Tech SV211KDVIGB.

Any ideas?

My System SpecsSystem Spec
31 Oct 2009   #2

7600.20510 x86

Update to latest video card drivers for both machines.

I tried looking for a driver for your unit but even the manufacturer's website says no drivers available. Yet they go on to show you a manual to download. Inside the manual says that there is a cd with driver included when purchased.

Did you try updating both machines with the driver from the cd?

Product Listing |

Best bet here is to deal with the manufacturer. If they can not help you, nobody can. Best of luck!
My System SpecsSystem Spec
31 Oct 2009   #3

XP MCE .... XP Pro 64 .... W7 U x64

My KVM is OK ... but I still have problems.

Display Guidelines for KVM Switches in Windows 7
By following these guidelines, IHVs can provide an optimal user experience in Windows® 7 with display devices that are connected to KVM switches.
I never had a problem until W7 improved my experience
My System SpecsSystem Spec

01 Nov 2009   #4

Windows 7

Thanks torrentg.

Yes, I had already re-installed the driver/software on both machines from the CD and updated the video drivers on both too.

No joy. I've contacted the manufacturer, but as you can't even download the original software from their website, I hold out little hope of a reply.

The KVM switch cost twice as much as Windows 7. I think I may go back to XP. As noyb points out, everything was fine until Windows 7 "improved" my experience.
My System SpecsSystem Spec
01 Nov 2009   #5

XP MCE .... XP Pro 64 .... W7 U x64

It seems that W7 needs to see the monitor ...
To decide how to "improve" your experience.

Boot without a monitor connected .. Or change monitors .. And it gets all confused.

I've looked for a button to turn this "nice" feature OFF .. But can't find it.

Sometimes .. A Shift+P can workaround this new annoyance.
My System SpecsSystem Spec
02 Nov 2009   #6

Windows 7

Sometimes .. A Shift+P can workaround this new annoyance.
No joy there either. This is really frustrating.
My System SpecsSystem Spec
02 Nov 2009   #7

XP MCE .... XP Pro 64 .... W7 U x64

Whoops .. I think this is the M$ key +P .. Sorry
I'm not sure which new and improved KVM <> Monitor features this fixes ...
There seems to be a couple depending on your setup/computer
My System SpecsSystem Spec
21 Jun 2010   #8
Rex Wu

Windows x, Mac OS x

According to "Display Guidelines for KVM Switches in Windows 7", Windows 7 checks all the status of the connected devices (including Monitor, keyboard, mouse, other connected USB devices and audio devices...etc.) and keep communicating to the connected devices all the time. So, if any of devices disconnected or "switched away", it will generate a HPD (Hot Plug Detect) to the OS. However, currently most of the KVM switches DO NOT handle the HPD well - For example, feeding monitor's EDID via DDC channel to all connected systems to prevent the display device HPD (most of the KVM switches were designed just feeding one channel/targeted system at a time, not to all the channels full-time. With partial EDID feeding, it will still cause display HPD error).

So, you need to find KVM switches which support "All-time Full DDC/EDID" to all the connected system for solve the display HPD issues. For the USB HID (Human Interface Devices - ie. Keyboard, mouse, touch screen and touch pad...etc) devices, you need to find KVM switches which support USB DDM (Dynamic Devices Mapping) to eliminate USB re-enumination HPD issues for Windows 7.

I'm very sorry to see the KVM industry's slow response to these HPD issues. It's becoming more important that KVM switches should keep the transparent features between users' shared console devices and connected systems (that's the ultimate goal of a KVM should be). Most importantly, more OSs (Linux newest kernel released in many distributions months ago) had also adapted the HPD features to make sure providing better device compatibility.

Hope you can find a better KVM switch to improve the quality of computing.
My System SpecsSystem Spec
21 Jun 2010   #9

Windows 7 Ultimate 64 bit

I use a USB KVM switch attached to one of my dual monitors on windows 7. This work flawlessly; however it is attached to the secondary display.

My XP Netbook has a similar issue tot he one that you describe on the same KVM switch, to resolve this I created a profile in the graphics display properties (in the graphics software, not windows 7) and I just switch to this if there is an issue.

In regards to switching, I'm sure windows 7 offers some shortcut keys to switch between displays; i'll look it up and get back to you as I can't remember it at them at the moment.

EDIT: The shortcuts that I was referring to are WIN+SHIFT+LEFT/RIGHT arrow (either arrow) Unfortuantely they only swap the selected window not the screen. If you have Business version or Ultimate also look at Win+P for the projector settings, as this allows you to flick between Extended, Duplicate screens etc (use WIN+P, RIGHT ARROW, ENTER to select the next option out of 4 available..... on my rig anyway). Hope this helps.
My System SpecsSystem Spec
21 Jun 2010   #10

W764BitEnt. 2K8R2 XPSP3

+1 Tim to the profile. See if you can disable the monitor, and then switch KVM.

Alternatively, there should be a way to disable it in devices, switch, then enable it again when you come back.

I'd give that a go.
My System SpecsSystem Spec

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