Thunderbolt KVM


first of all, thanks for all the knowledge you collected around here, have been lurking for a long time. I love tinkering with hardware, but am not a pro by all means, so I’m a bit out of my comfort zone with the details surrounding USB/Thunderbolt.

Problem description:
I have three hosts (2x TB3, 1x USBC) that I want to hook up to my peripherals. Currently, I have to manually switch TB3/USB cables + monitor inputs. I would love to find a KVM (+ possibly audio) solution that doesn’t limit my hardware capabilities (too much).

As with many of you, my setup is a bit special:

  • The hosts are:
    • Macbook Pro (TB3)
    • Rack-mounted PC with ASRock x570 Creator (Corning optical TB3 cable)
    • ASRock 4x4 Box NUC-like on my desk (USB 3.2 Gen2)
  • I use dual monitors (4K + Samsung Neo G9).
  • At the center of my Thunderbolt setup, I have the Caldigit TS3 Lite (Alpine Ridge, only DP 1.2).
  • To be able to use HDR with the G9, I use a StarTech TB32DP14 (Titan Ridge, TB3 on TS3 Lite → 2x DP 1.4) to connect both displays.
  • My speakers are connected to the dock via optical S/PDIF. (also support HDMI ARC, coaxial S/PDIF, analog and Bluetooth)
  • The 4x4 is wired separately (USBC + HDMI 2.0a, currently no sound)


  • Can’t use a USBC KVM directly since the optical cable only works with Thunderbolt 3 ports.
  • Can’t use the 4x4 as TB dock host since it would need to support TB.
  • Want DP 1.4 for Neo G9 HDR (at least from the TB hosts).
  • Not sure if USB bandwidth/peculiarities will limit the Neo G9 framerate vs TB3.
  • Would love to have unified digital sound output as well, not mandatory.

Current workaround:

  • To switch between TB devices, manually switch TB cables.
  • To switch to 4x4, manually switch keyboard/mouse cables and monitor inputs.

Conceivable solutions:

  • Thunderbolt 3/4 KVM with support for USBC hosts (most elegant, but doesn’t exist afaik)
  • Level1techs 4 input USBC KVM with DP 1.4 + somehow going from TS3 Lite to it (Would need Displayport 1.4 + USB → USBC adapter for DP 1.4 compatibility) [edit: this one doesn’t exist and doesn’t fit, it’s only 2 input + 1 x DP 1.2 out, probably USB bandwidth doesn’t allow for much more?]
  • Standard 4 input DP 1.4 KVM with separate dock for the Macbook (probably the safest [edit: and only] route atm)
  • Wait for optical TB4 cables[1] and/or hypothetical USB4 KVM (will that even work with TB3 hosts?)
  • Anything simple I’m overlooking?

Sorry for the long description, I hope my intention is clear. The whole thing feels like a big knot in my head lol. I’m very thankful for any help untangling it, even just comments on the feasibility or on what to watch out for.


TB3 ---------\ 
TB3/USBC ----  KVM -> 2x DP 1.4?
USBC --------/

[1] /r/Thunderbolt/comments/j2wte2/corning_thunderbolt_3_cables_finally_available/g78awfr

I would never want a Thunderbolt KVM, there are a ton of issues with just the docks. TBolt is great when it works, and a pita when it doesnt.

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I was checking this some weeks ago and there is a company named Corning that has optical thunderbolt cables. Price is outrageous at like 300$, but the option exists. I consider getting one to clean up my desk and move PC to another room. I only have one device, so can’t comment on the rest/majority of your case.

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I actually do use one by Corning (to declutter my desk space, still surprised how well it works), but those are TB3 and can only be connected to TB3 ports. The reddit post says a future TB4 one could potentially work with USB ports as well.

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Yeah the price on optical cables suck due to low volume. I do see a future when they all need to be optical as we just keep pushing more and more pixels and need lengths that cant do that with copper.

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