Windows – Audio issues during KVM switch

The HDMI standard itself does support audio. However, whether it works for you depends on the specific card, though all the recent cards I know of from AMD or nVidia do support audio via HDMI.

Some older cards only have partial support, and require a S/PDIF connection to a header on the motherboard/sound card. I had a MSI nVidia 9500 GT that did this. Example 1. Example 2.

Unfortunately, graphics card manufacturers don't seem to put the HDMI audio details into their spec sheets (at least MSI doesn't). Therefore, it's difficult to be certain. You may have some luck contacting the manufacturer, asking the retailer or searching for other users of the card model. Failing that, you can make some assumptions - a brand new card now probably supports it.

Then there's software support. I'm not certain what the situation with Linux is, but audio out via HDMI does come up as a separate sound device on Windows when you have a discrete video card. This may require special drivers, and you might have to change your default output device.

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 :

• Custom Resolution Utility
• PowerStrip (shareware) was the best of its kind, but is not updated since 2012. It is still available for download (but no idea how long it will keep on working).
• Microsoft also provides a method for Overriding Monitor EDIDs with an INF which is not that easy to use.