Hello all,
I want to start off with saying that 1.) I am fully aware of Apple’s apple-isms and realize that sometimes things just don’t work the way they should on Apple hardware and 2.) I have spent some time searching the forums on this issue without finding anything that matches my problem.
My setup is a 2x3 L1 KVM (2pc, 3 monitor), a built Windows gaming PC with RTX 4090 as graphics and 5950X processor, an M1 Mac Mini (2020), a pair of Acer 1080P monitors and a single LG 4k Gaming monitor.
My Windows machine has a trio of DP1.4 cables connected to PC 1’s inputs on the KVM. My Mac Mini has a Thunderbolt to DP1.4 cable connected to input 1 and the Mac’s HDMI output via an active HDMI to DP converter powered by USB connected to input 2 on the PC 2 side.
If I select PC 1 on the KVM which is my Windows machine, everything works flawlessly and all of my monitors are able to work at full resolution and refresh rate.
If I select PC 2 (Mac Mini) on the KVM, only my LG monitor shows input, and the Acer monitor that would correlate to input/output 2 shows no signal.
In an attempt to troubleshoot, I swapped the Input 1 and Input 2 connections at the KVM, so that my LG monitor is now getting its input via the HDMI to active DP converter, and the Acer would be getting it via the thunderbolt to DP converter. Interestingly, the LG monitor lit up again, but this time only at 60Hz given the HDMI limitation, but the Acer monitor still stayed asleep.
Another interesting tidbit is that in the initial configuration, where the LG monitor is receiving video via the TB to DP adapter, and the Acer was going via the active adapter, the adapter itself was showing up on my Mac’s display settings at 1080P, so something was happening, but no signal still.
At this point, I’ve proven that all 3 monitors are happy to receive signal from the KVM, and that my active HDMI to DP adapter can work since it does on my LG 4k monitor. I’m stuck in determining if my problem is my Mac Mini, or some kind of compatibility issue with the Acer monitors given the double-conversion (either TB to DP to HDMI or HDMI to DP to HDMI).
I’m hoping someone smarter than I can assist here.
Thanks!