KVM Setup with HDMI 2.1 and DP 1.4 - Config Assistance

I currently have two PCs (work + personal) with a 3-display setup (48" LG C1 TV + 2x 27" LG UHD monitors). The personal PC has a 40-series Nvidia card and the work PC has a 30-series Nvidia card. All displays can do 4K 120 and are G-sync compatible. The C1 TV is only HDMI 2.1 while the LG monitors can do HDMI 2.1 or DP 1.4. My current setup uses a 3-display HMDI 2.1 KVM where I need to do one conversion from each PC of DP 1.4 to HDMI 2.1 with a Club 3D adapter (each card has 2x HDMI 2.1 outputs but equal or more DP 1.4 outputs).

The setup works enough…but there are a couple of issues with the setup where I’m always looking for something more reliable. One issue is that the DP to HDMI adapter isn’t compatible with G-sync (I’d like to utilize it on all monitors). Another is that I’m not entirely happy with the HDMI KVM, it’s prone to intermittent issues while switching and the switch does not work consistently.

So what I’m thinking of doing is going with the 1.4 Display Port KVM Switch - Triple Monitor - Two Computer (10 Gigabit once available again). Then I just need to convert the DP out to the LG C1 from DP 1.4 to HDMI 2.1. I’m going to try a SIIG adapter (CB-DP2611-S1) that supposedly has the Reltek RTD2173 which can do the DP to HDMI conversion at 4K 120 and HDR 10 (not entirely sure if it’ll pass G-sync). But if that adapter doesn’t work, would the L1Techs EDID Feeder DP 2.0 to HDMI 2.1 essentially do the conversion from DP 1.4 to HDMI 2.1?

And I guess the follow-up there is, in general, can I use a DP 1.4 to HMDI 2.1 converter on the output of the KVM to run to the LG C1 and retain all the features I want (4K 120, HDR, G-sync)?

(I also don’t care about passing audio, so it that doesn’t work, no biggie)

I tested this just a few days ago and I didn’t have any issues converting displayport out to hdmi, BUT let me test with the new monitor we bought. It’s 4K 120Hz, gsync, all that good stuff.

Noooot sureee about GSYNC. I’ll check that too

Thanks for looking into it. I wouldn’t be surprised if G-sync didn’t work. I found the one-sheet for the VDDC-8K220, and there’s a note that states “DP 2.0 Input Model Do Not Support VRR / QFT / QMS.” But practical experience is best if you’re able to test it.

I’m also curious what you end up finding on the G-Sync/Freesync front and whether that’s supported in the scenario listed above. Thanks!


The HDMI KVM has variable refreshrate compatibility, but it is actually a hdmi-style freesync-only kinda thing. Freesync of course is compatible with Nvidia cards, just clarifying it’s not exactly g-sync technology, and there can be edge case compatibilities on the hdmi side. hdmi freesync != displayport freesync.

A feeder or adapter DP → HDMI will disable any variable refreshrate technology; i.e. both freesync and g-sync. That is not the KVM but rather just how that works in general it seems.

the displayport kvms perfectly pass through the signal unchanged (for DP monitors. Possibly for some theoretical DP to HDMI adapter freesync would work with this, but no adapter for this actually exists).

wendell uses a LG CX with the hdmi kvm and freesync and likes it. But hdmi freesync is not a bug-free experience “because hdmi” nothing to do with the kvm really.

1 Like