Monitor Issue After Introducing a KVM

Hello all. Having an issue I could use help identifying, and solving if possible.

Here’s my setup:
KVM Port (computer) 1 -

Dell laptop connected through USB-C to KVM.
Also connected to eGPU through USB-C
3 monitors connected to KVM via DisplayPort

KVM Port (computer) 2 -

Home built MSI Z690 Carbon motherboard, MSI GTX-3080 GPU
Connected through USB-C to KVM

Monitor 1: Samsung 49" Odyssey Neo G9, connected to KVM via DisplayPort
Monitors 2 & 3: Samsung C2FG7x 31" connected to KVM via DisplayPort

Here’s the problem: When I was running without the KVM, everything was fine. Since introducing the KVM, the two C2FG7x monitors are fine and work perfectly. The Odyssey (model LS49AG95) works, but every 10-20 minutes it loses the DisplayPort signal and goes dark.

If I power cycle the monitor, it comes back. Doing this 4-5 times an hour is pretty frustrating, though.

Any ideas?

TIA,
Rob

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It could be a cable quality issue. Try getting higher quality cables, and use shorter cables if it won’t cramp usage to improve signal quality. It could also be a problem specific to that KVM.

I very strongly suggest watching this video.

This company makes good cables, make sure you get ones that are rated for your required resolution and displays https://www.cablematters.com/ I believe wendall has suggested that company in a few of his videos. (correction - Wendall suggested the Club3D cables I mentioned next… GN Steve suggested the CableMatters cables.)

I personally use Club3D cables. Amazon.com: Club3D Again make sure the cable you buy is properly rated for the screens you are using. (higher quality cables are especially important for modern high resolution and high speed displays.)

  • Often the cables that are included with monitors are pretty crap and can reduce signal quality due to their poor construction. This usually isn’t a problem unless you are doing things like using a KVM which introduces extra connections to the line, or if the monitors are higher resolutions and speeds.

Signal quality issues can cause intermittent problems such as you described.

  • Regarding the KVM, some monitors require specific communication and low quality KVM’s might not be able to properly handle the traffic in both directions fully because of the switching technology specific to certain KVM’s, this can also cause the issues you mention. So I suggest also looking into the particular KVM you are using and see if other people have had the same issue. If that is the case, you might need a different KVM entirely.

Also check out the KVM’s from https://store.level1techs.com/

Just thought I’d follow up with an update. It took a week+ due to shipping delays.

When I purchased the KVM, I bought 2 DisplayPort cables from Amazon. The label says the brand is “JSAUX” and they are each 6 feet in length.

After watching the video and having a conversation with a friend, we also determined that the DisplayPort run length from the monitor to the KVM, and then the KVM to each computer, was nearly 10 feet.

Taking the video’s advice, I purchased two Club3D cables, each only 1m in length. I didn’t need long cables because the GPUs and the KVM are close together. A couple of hours after swapping the cables, I have not had my screen go dark yet. Without directing aspersions at the JSAUX label, it’s entirely possible that simply shortening the cable run between the monitor and the GPUs is what fixed the problem.

Regardless, the problem appears solved so thank you for the advice!

1 Like

Very glad to help! =) Enjoy your new setup!