Following up on this because I’m having a very similar issue with an M3 Macbook Pro and the Combo USB-C Power Delivery & DisplayPort 1.4 KVM - Dual Monitor.
My Linux PC works fine: it’s outputting to both monitors from an Nvidia GPU (one using DP Alt over USB-C and one DisplayPort). It’s running 2560x1440 at 144Hz, and after switching to 3m Fibbr DisplayPort cables for the KVM ↔ monitor connections all of my flickering issues have gone away on that side (I also had to turn off AdaptiveSync in the monitor settings).
But I’m still having issues with the Macbook. They’re very similar to what’s described here - periods of no issues that are much more persistent after switching the KVM to the PC, then back to the Mac. The Mac is connected to the KVM via a 1m Cable Matters 80Gbps Thunderbolt 5 Cable. I also ordered one of the Moshi USB-C to DP cables, still waiting for that to arrive so I can test with two monitors (and see if that setup has this issue).
I’m using the 27GL83A-B for my monitors.
I’ve tried debugging everything I could think of / saw recommended here (aside from the ferrite clamps mentioned above). I switched from the L1T USBC to the CableMatters Thunderbolt; upgraded to the Fibbr DP cables (which fixed my issues on the Linux side); tested the Mac output on both monitors; tried switching USB-C ports on the Mac; installed BetterDisplay and tried various settings (e.g. changing the refresh rate doesn’t fix the issue, happens at 144Hz, 120Hz, 100Hz, and 60Hz). The KVM is set to the 4 Lane/USB-2 setting.
Interestingly enough, I started this journey by ordering the USB-C KVM Switch v3 (with USB Power Delivery / 135watts) and wasn’t seeing these issues (I still have that one at a different workstation, and this isn’t happening). It was after swapping in the dual monitor KVM that these issues began, and after updating all of the cables/debugging monitor settings I ended up here.
Curious if there are any ideas here, or if anyone else has figure something out here. Thanks!
Also the issue I’m getting is mostly screen artifacts randomly popping up, I’m unsure if the blackouts are as big of a problem for me (might’ve fixed it by changing some settings earlier, remains to be seen).
Another update, and a question: I was able to test with my friend’s “HDMI 2.1 KVM w/EDID & Serial Control - Single Monitor - Four Computer” L1 KVM, and that worked a lot better. It also improved/fixed other issues I was having around monitor disconnects on the Linux side.
My question is: would putting one of these between each of the monitors (using the DP ports) and my non-EDID KVM work the same as the EDID KVM?
I like the feature where the inactive computer ‘thinks’ that the monitors are still connected when they aren’t, but it seems like that wouldn’t be the case if the EDID cloner is between the monitor and the KVM? And aside from that, am I right to think that perhaps the repeater could at least help with the screen glitch issues?
This would not work the same in the sense that this product is DisplayPort 1.2 / HDMI 2.0, so it is limited to 4k @60Hz. Otherwise, yes, this is hardware monitor emulation.
For the Mac, are you using DisplayLink hardware…? 1440p at 144hz should be no problem via USBC and the KVM. Have you tried aznotrher USBC cable just to make sure yours isn’t faulty?
Nice, I’m using 1440p @ 144Hz so I think that limitation is okay.
And re: hardware monitor emulation: if the EDID emulator is between the KVM and the monitor, would the signal still reach the inactive computer? I’m not quite understanding how the inactive computer would see a signal from the emulator that’s on the other side of the KVM, when the KVM would be connecting the active computer to the monitor (and, therefore, the EDID emulator as well). Just want to make sure the setup I’m envisioning makes sense before buying, because that’d be great if it works that way.
I initially tried with this L1T cable:
then switched to this (1m):
OP was saying they tried various cables (including the Club3D) and still had this issue, so I figured I’d ask before running through more cables. But anything’s worth a shot at this point
Essentially, yes, our feeders avoid computers from deactivating DisplayPort ports while not in use and read the necessary EDID information from the splitter unit itself or copy EDID from the EDID-compliant monitors (DP or HDMI), to ensure an accurate output display.
I have no clue why the USBC to USBC connection wouldn’t be working, did you want to setup an RMA?
Gotcha, that’s good to know - I started to think EDID repeater would have to be connected between the KVM and the computer itself, then it would ‘remember’ the EDID info → forward it to the inactive computer. But if connects between the monitor and KVM like you’re saying, then that halves the number of required EDID repeaters which is nice
Re: RMA, bad timing unfortunately - I ended up shipping back my KVMs today and had asked for a refund, even if the screen glitch issues were fixed I kept having screen configuration problems that I figured EDID would fix. So I’m currently planning to wait for a dual-monitor EDID KVM to be in stock
