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SV211DPUA (https://www.startech.com/Server-Management/KVM-Switches/2-Port-DisplayPort-KVM-Switch~SV211DPUA)

I followed the startup instructions here exactly: https://www.startech.com/faq/kvm-switches-setup

and Also the troubleshooting here: https://www.startech.com/faq/kvm_switches_general#SV211DPUA - by switching KVM and External cables, and performing the startup all over again, for example.

On my DESKTOP PC, which has a GTX 1070 with the latest drivers, and Windows 10 fully updated including the creator's update, this KVM switch always has issues which I will describe in more detail below. The Desktop PC has 2 HDMI-connected monitors which are NOT going through any KVM. They are always on. The KVM controls only one monitor via display port.

On my Suface Pro 4, it works every time (the 2nd PC connected to the KVM).

When I first turn on my Desktop PC, the KVM works fine. Then I switch to my surface, still works fine. Finally, I go back to my DESKTOP PC, and the HDMI-Connected screen (no KVM) begins to flicker on and off a few seconds at a time. The DP connected screen (through KVM) stays completely black, but the monitor light is blue (meaning it's not in idle). If I disconnect the DP cable from the DESKTOP PC, or turn the kvm-connected monitor OFF, the DESKTOP PC loads the 2nd HDMI-connected monitor without issue.

At this moment I have disconnected the display port cable from KVM-to-Desktop, but am still using the KVM to switch my controls (both mouse and keyboard) and use my other 2 remaining monitors on the desktop PC successfully.

I opened a chat w/ Startech, and they were actually quite helpful. Below are the further tests performed:

Test 1

  • Please connect the DP monitor directly into your Desktop as a third monitor (not passing through our KVM).
  • ok completed. Monitor is up. So right now, I have all 3 monitors working just fine. And I can move between my SP4 and Desktop using the KVM for controls only, works great actually.
  • Now I simulated the KVM's display switch by disconnecting the DP cable from your desktop, waiting about 20 seconds, and then reconnecting it.
  • The monitor came back instantly when i plugged it in again after ~20 sec.

Test 2

  • Started on the Desktop. Only the Displayport monitor was connected to the desktop at this time (disconnected the other 2 HDMI directly-connected monitors). DP was connected THROUGH the KVM. No issues here yet.
  • After I switched to the SP4, it worked fine on the surface too.
  • Then I switched bakc to the desktop, and I saw nothing on the screen (no connection basically, but it did seem like it was flashing a little bit, trying to do something).
  • After a minute of that, I tried to disconnect the KVM, and connect ANY of the monitors directly again to my desktop PC, but none of them connected. HDMI or DP, didn't matter.
  • Then I thought maybe it was due to mouse/keyboard being non responsive, so I connected them directly via usb to the desktop. They wouldn't even get powered. No red light on mouse, no caps lock on keyboard.
  • So I had to shut the PC down manually, restart, and everything came back.

However, they conclude that it's not hardware related to the KVM as the switch is very simple (see below).

It is nothing more than a hardware switch. Although the USB connectivity can be more complex depending on the models, the actual display switching has no chipset or particular technology other than a physical cable switch. There is no software, drivers or associated technology that could be involved either. Furthermore, we also know that your KVM isn't defective since it works on other computers. The absolute only difference from our KVM's usage and an actual manual cable disconnection is the fact that the KVM keeps the cable's connection alive. When switching, the computer loses the monitor's information (identification information), but remains aware that a hardware connectivity is there. This, normally, doesn't cause any issue on the computer's side other than resolution changes and monitor re-arranging.

So finally, I'm asking about what on my software or hardware side on my Desktop PC could cause this issue and if anyone has more items to try or look into to fix it.

Thank you!

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You could also try powering off the KVM and powering it back on. Note that unplugging the power cable does not completely power off the KVM switch as any USB cable connected to the switch while also connected to the PC will also provide power to the switch. You should remove all USB cables connecting the KVM to a power source before removing the power source.

There is a very good explanation in the post KVM switch with win 10 which says:

I don't think it is Windows 10 caused the issues but the design concept of the KVM switches with those cases. I had using ConnectPRO Plus serial KVM switches with Windows 10 systems for a long time, and I never experienced the resolutions resizing issues.

Most of KVM switches in market are designed with emulation-base technology in devices sharing including for sharing the monitor, so when the more advanced OS, like Windows 10, is upgraded to those emulation-base KVM switch will have difficult in emulating /fitting the timing to the systems upgrade to Windows 10 which monitoring the I/O hot-plug and connected devices' status all the time.

I don't like to give suggestion of just changing the KVM switch and find a KVM switch based on DDM technology, but looks like there is no other solution then using more advanced KVM switches based on the DDM technology (Dynamic Device Mapping). Of you may want to using an EDID emulator putting it between each connected PC/system and your old KVM switch to keep feeding the EDID of your monitor to the Windows 10 PC/system.

DDM refers to Dynamic Device Mapping defined as:

With DDM (Dynamic Device Mapping) Technology, the communication between shared peripherals and all connected systems are maintained 100% of the time, even as a user switches between the KVM ports. This makes generic device emulation unnecessary as the DDM allows each connected computer system to believe all connected I/O devices are remaining connected even as the KVM switch might move to another port.

I note that the SV211DPUA does not seem to support DDM, as is also implied by the answer you got from Startech. You would need the heavy-duty SV231DVIUDDM for that, at about $100 more.

A software solution in Windows might be to statically set the EDID of the monitors as constant, so Windows will not try to contact the monitor when it is not there.

If one has an NVIDIA Quatro display card, this can be done via the NVIDIA control panel.

One can also use a utility that creates a custom EDID profile, as these utilities set up a permanent profile in Windows so it does not contact the monitor.

Here are a couple of utilities :

  • Unfortunately the software options are a non starter, ad my SP4 is for work and I cannot add any of those. Can you explain further what exactly I need to do for the EDID profile? I am looking at a lot of stuff here with out much idea where to begin to try something =). Thanks – Shackrock Aug 16 '17 at 10:24
  • Further, I don't a 1070 not a quadro so I don't have EDID settings available in the card - that being said, I have downloaded CRU as recommended, but I'm not sure how to set it as a static profile... – Shackrock Aug 23 '17 at 13:26
  • With this as a starting point, and MUCH googling the final fix was as follows: (1) use CRU to do as follows: Follow instructions here w/ CRU: forums.geforce.com/default/topic/966823/… - AND change monitor to DP 1.1 instead of DP 1.2 mode - AND to disable "USB selective suspend setting" in power settings on the desktop. Would appreciate you updating your answer with this info as well for others! Thanks. – Shackrock Aug 23 '17 at 15:02
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I have a similar issue with my inexpensive Monoprice monitors - occasionally on switching with my Startech DP switch, the monitor stays black. However, I am using an nVidia professional card with EDID set from a file, not read from the DP connection, which prevents all my application windows from moving to one monitor when I switch the second monitor.

I have decided the issue is in the monitor - it doesn't recover properly from the switching. My fix was to hook up the monitors to a remote power switch (since they have no power switch) and cycle power when this happens. That always fixes it.

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