Question Screen flashes/flickers while switching inputs due to kvm

Dec 10, 2020
My monitor has a direct DP connection to my PC and an HDMI connection to a KVM which then leads to my PC and my consoles. The sound goes via the KVM and is extracted from the HDMI signal to go to my amp (to give some context for the setup).
The issue I have is when the KVM is set to connect to my PC (otherwise I have no sound) and the monitor then has 2 active incoming connections.
When I switch on my monitor, it shows the DP connection. Three seconds later it does a quick blink of "black, image, black, image", then pauses a second and does it once more as it detects the KVM's HDMI signal. For some reason this also breaks the night light functionality in windows (it's warm in the beginning and cold after flashing while still enabled).
If I switch off my KVM, the issue goes away. If I unplug the hdmi cable from my monitor, the issue persists but only does the "black, image, black, image" once. This makes me suspect that it is not the monitor but something in windows (because the PC is still connected to the KVM).

This did not happen from the start when I had this setup. After a major windows update, it suddenly started happening. It lasted for about a year and then with another windows update it was suddenly resolved. I did not update my Nvidia drivers at that time.
Now tonight I had another small windows update and I also updated my Nvidia drivers and the issue came back. I checked windows update which had the big 20H2 available so I installed that but no change. No more updates are available.

My conclusion is that it is the windows update in which they broke it again but last time it took a year for them to fix it and I really don't want to wait that long again (especially with it breaking night light which I can only fix by restarting explorer manually). And by the way, I have night light on permamently and none of the programs like f.lux seem to support that so I can't replace it.

Update: I found lightbulb ( which solves my night light problem.
Update2: but the flashing seems to disable lightbulb so that's barely an improvement
Last edited: