Same monitor via KVM, but limited to 60 Hz → no flicker
Mouse + Keyboard connected to dedicated KM ports on back of KVM.
Other connected devices via USB self powered hub connected to KVM USB port:
Webcam, Sound Blaster Katana V2, Seagate backup drive
Symptoms
On desktop, display flickers repeatedly when:
PC first boots, or
Switching inputs from laptop → desktop.
Flicker can be anywhere from 3–7 cycles. Sometimes the screen stays dark for up to a full minute. Occasionally, it does not recover at all (requires RDP or reboot).
Direct connection (GPU → monitor) = perfectly stable.
After the initial flicker storm (first 1–2 minutes), the system usually stabilizes and rarely flickers again while in use (gaming or desktop work).
What I’ve Tried
Monitor on latest MSI firmware available from MSI website
Tried refresh rates 60 / 120 / 240 Hz. HDR on/off. VRR/G-Sync on/off. No change.
Multiple rounds of EDID learning (9s hold) and pass-through EDID (3s hold). Same behavior.
Full OS wipe/reinstall with clean Nvidia Game driver. No change.
Laptop input (60 Hz only) basically never flickers.
Observations
I am 100% certain the issue only occurs when routed through the KVM. Monitor to GPU directly has no issues at all.
Behavior looks like the GPU/KVM/monitor are struggling to negotiate EDID and/or FRL link training during startup or input switching.
Once the link is stable, it almost always remains solid for extended sessions.
Doesn’t appear to be a simple bandwidth overload (flicker also happens at 60 Hz), HDR disabled, etc.
Question
At this point, I’m not sure what else to test. Is this likely an EDID handling quirk, a VRR/HDR/FRL negotiation bug, or something else with the HDMI 2.1 switching matrix? Any advice on further triage or known firmware tweaks would be greatly appreciated. Thanks in advance
we should probablyorder some of these cables to try. Could be picking up external interference… maybe worth trying some ferrite cores. placing one about 1.5 inches from the end of the hdmi cable on the kvm side on the cable from the pc.
I’m also getting intermittent black screen flickering with the same KVM…only happening on one of my monitors with GSYNC enabled.
Occurs more frequently when gaming (4K @ 240Hz, 10-bit HDR or SDR), however also flickers when idling at desktop (SDR)
System
Windows 11 (latest updates)
PNY Nvidia RTX 5090 (latest Game Ready driver)
AMD 9800X3D
64 GB RAM
x2 MSI MPG-321URX-QD-OLED monitor, each 4K @ 240Hz with DSC
All cables are using Ruipro 8K Fiber HDMI 2.1, mix of 3/6/10 feet. Non-issue monitor is using a CalDigit DP 2.0 → HDMI 2.1 adapter. Monitor with flickering is directly going from 5090 HDMI 2.1 port into KVM to the monitor…no adapters
Tried lowering the refresh rate and bit-depth on my other monitor and kept my “gaming” monitor the same…still flickered
DDU’d drivers with clean reinstall…still flickered
Power cycled KVM and monitors, and reset the KVM settings…still flickered
Any chance we can get a video? I would like to see how it’s flickering. Does long power cycling (leaving off for several minutes with everything unplugged from it) the KVM do anything? If you plug the monitor’s power cord as well for several minutes, once they connect again they will re-handshake
I would try a club3d hdmi copper cable. or two if you have them. the audio working is weird… it blinks like its hdcp decode failure, which is possibly noise on the line.
I have like this flicker with Xeon+AST 2600+RTX 5080 combo and Alienware Oled with KVM.
On the bios enable the integrated gpu what is in the ondie the cpu.
For me work this.
Thanks for reaching out, Wendell! For reference, what is the total maximum HDMI 2.1 copper cable run length (GPU → KVM → Monitor) allowed with these HDMI 2.1 KVMs?
My runs would be semi-long (10ft + 6.6ft) and wanted to ensure I stay within the safe ranges without signal degradation. I originally went with all Ruipro fiber cables to avoid those potential issues
If I move things around in my office, I can possibly get away with 6.6ft + 6.6ft as my minimum run length.
Is there any kind of debug data, dump file, telemetry (anything?) that can be exported from the KVM unit itself? Is there a debug mode we can enable to see handshakre, re-negotiation timeouts, etc for the hardware devs to look at?
I’m happy to purchase and try any cables that anyone suggests, but considering the behavior is so different between my Lenovo laptop and my Desktop GPU, I find it dubious at best that the cables are the culprit.
For me: power cycling the KVM doesn’t change the behavior. As I’ve typed this out, the monitor has flickered twice, each time about 10 seconds-ish each. My Desktop GPU has been off for the last several days, and the flickering occurred after about 5 minutes of being back on.
Is there any possibility we got a bad batch of KVMs and they simply need to be RMA’d ?
For whatever this data point is worth: my same setup worked 100% perfectly fine using my old Dell 49" Ultra Widescreen (which my MSI has now replaced) which had an internal KVM built-in to the monitor. No problems, no flickering… same HDMI cables, same GPU, etc. Granted this was a 5+ year old monitor which only went up to 60hz and SDR, but, this flickering only started after introducing the L1Techs KVM into my hardware chain.
I will try to capture a video on my end to share as well. Thanks everyone.
Still getting the same flickering style from my previous video on my monitor with both the certified Silkland and Club3D cables. KVM and monitors were power cycled after replacing each cable brand/run
Club3D HDMI 2.1 Certified Copper (Flickered): GPU to KVM - 6.56ft, KVM to monitor - 3.28ft
Silkland HDMI 2.1 Certified Copper (Flickered): GPU to KVM - 6.6ft, KVM to monitor - 3.3ft
When going from my GPU directly to my monitor (thus bypassing the KVM), there isn’t any flickering
@wendell is there any telemetry or actual data or stats we can export from the KVM device itself? Is there any way to debug this in a more deterministic fashion to see what’s actually going on during the handshake when the flickering occurs? Thanks!
