My setup have 3 monitors and two systems. All of the monitors are 4k and one of them is 144hz. I know the total bandwidth is limited at 8k@60 so the high refresh rate one is set to 120hz in the os on both systems. When all the cables are connected correctly, it would sometimes for a while if I don’t switch to the other system, but most of the time the high refresh screen get stuck in scanning signal while the other two screen keeps flashing to reset main screen as if the high refresh rate display keeps connecting and disconnecting. I’m not sure what could be the cause. Could it be some compatibility issue with specific monitor models?
Other Notes:
The high refresh monitor is Cooler Master gp27u.
One of the systems uses Windows while the other uses Ubuntu.
I tested all of the cables I used by connecting the system directly to the displays and they all seem to work as intended (bandwidth-wise).
This is a red herring when it comes to the KVMs. Connecting a cable to the PC is not the same as connecting a cable through the KVM. This is because of how the KVM sees cables:
Can you list what cables you’re using? How long are they?
Welp I did not realize there is a limit in total cable length from PC to monitor. Mine is about 16ft in total so I guess that would be the issue then. Would a display port signal repeater help?
I’ve seen people say this helps. I’ll link the specific video I’m thinking of:
You can find the product he references here:
Club3d is a brand we use frequently, they’re pretty reliable.
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This is expensive, but you could buy fiber optic displayport cables that are virtually lossless in bandwidth. I’d recommend exhausting other options first
Thanks. Unfortunately the club 3d one is weirdly expensive on Amazon Canada, so I’ll probably get something similar from Cable Matters. I’ll update the result after I receive those repeaters.
So I got 3 repeaters along with 3 short dp cables and I connected all of them to the display out but the issue persists. On the first start up it worked fine, then the issue immediately returned after I did a reboot. I thought it could be a distance thing again so I tried to put the repeaters on the input side but nothing changed. What should I try next?
I have 3 cable that came with the monitors so I don’t know the exact models for those. Other than those, I have 3x10ft dp cables from Maxonar, 3x6ft cables from UGREEN and 3x1.5ft cables from Silkland. 12 cables total.
As a general rule of thumb, I wouldn’t trust cables that came with your monitor
Yeahh… I’d recommend getting some shorter high-quality cables.
Can you try higher refresh rates? 120hz is about the max without DSC. So, if you set the refresh rate high enough to enable it, it might actually be easier to display than 120hz. The Cooler Master gp27u for instance goes up to 160hz.
I’ve done some digging and it seems like there’s some firmware bug with gp27u that causes the scanning signal loop. It can be temporarily fixed by power-cycling the monitor but it will come back after reboot. Perfect excuse for a monitor upgrade I guess
