Question What is the best way to set up these three DisplayPort PC's with a KVM and HDMI Display?

[Calab]

I am trying to figure out the best way to connect my three computers to my display as it currently does not work well.

I have three computers. The first runs Windows 11 and has an RTX 3060 video card offering both DisplayPort and HDMI. The second is my work laptop running Windows 10 and uses and Intel/AMD video combination and only offers a DisplayPort output. The final machine runs Linux with a Quadro T400 video card that only has mini-DisplayPort outputs.

My display is an LG QNED75URA 43" TV, which has a great picture - when it's working. This TV has three HDMI inputs.

All three computers are currently connected through a 4 port Blackbird KVM. This KVM only has DisplayPort inputs, but does have both a DisplayPort output and an HDMI output. The KVM is said to support up to 4K video at 60hz with a 4:4:4 colour depth.

Right now all three computers are running 4K, connected to the KVM using DisplayPort. The KVM feeds the display signal to my display using the HDMI connection. This "kind of" works as long as I keep the refresh to 30hz or less, but has a hard time when switching PC's or resolutions. Many times, when I switch, I will just get No Signal and will need to restart to get the display back. When I boot, most times I don't see the boot screen and can't see BIOS settings if I hit the Delete key.

I would like to try and get the signal "cleaned up" so that I can run with 4K at 60hz on all the machines.

A few ideas I have are:

1. Use a DisplayPort to HDMI adapter from the DisplayPort on the KVM, instead of letting the KVM do the HDMI conversion. A DisplayPort 1.4 converter runs about $30 CAD.

2. Replace the KVM with an 8K DisplayPort model and convert the output with an adapter to HDMI.

3. Replace the KVM with an 8K HDMI KVM and convert each of the DisplayPorts on the computers to HDMI. This is a bit costly - Around $120 CAD for the KVM and $30 each for the adapters.

Any ideas why my current setup does not work well? Are there any other solutions that might work?

 

[Ralston18]

As I understand your post:

Computer 1 > RTX3600 >DP output
Computer 2 ( work laptop) > DP output
Computer 3 (Linux) > T400 > mini DP output

The requirement being that all three computers "share" and (one at a time) a LG QNED75URA 43" TV, with 3 HDMI inputs.

My thought:

Get a mini DP to DP converter for Computer 3.

Then proceed with idea 2.

Seems the simplest to implement and mimimizes the need for adapters.

Easier to troubleshoot.

= = = =

However not sure about this part:

"Right now all three computers are running 4K, connected to the KVM using DisplayPort. The KVM feeds the display signal to my display using the HDMI connection."

To confirm - if each computer is directly connected the LG TV there are no display issues - correct?

This LG TV?

https://www.lg.com/us/tvs/lg-43qned75ura-qned-4k-tv

https://www.lg.com/us/support/software-firmware-drivers

Do all three computers have the applicable drivers installed?

Just my thoughts on the matter.

 

[Calab]

I ended up going with option #1. A 1.4 DisplayPort to 2.1 HDMI converter with a new 8K HDMI 2.1 cable. It was the cheapest solution and easiest with my setup. I already had the mini DisplayPort to DisplayPort adapter for computer #3.

Now #1 can do 4K, at 60hz with 12 bit RGB color.
#2 is doing 4K, but only at 30hz. Screen stays black if I try 60hz. It's my work computer, so 30hz is fine.
#3 is also doing 4K @ 60hz if I remember correctly.