Question KVM DisplayPort flickering and lines on screen, only with 1 computer

Apr 6, 2021
Hi, hope you're well!
I hope I'm posting in the right place

I've been working with computers for ~16 years and I have a really interesting problem here.
I have a DisplayPort KVM with two outputs.
I have 1 computer, Luxa, and one new computer, MechBot.
Now when Luxa is connected through the KVM, it flickers and there's nasty lines across the screen on and off. This is before Windows even loads, during the BIOS even, so it can't be a software issue. Connecting it directly to the monitor is fine. It does this issue with both ports on the KVM. I've also tried all 3 DisplayPort outputs on my graphics card. I've purchased and tried a total of 4 different DisplayPort cables - the issue still exists with all of them.

MechBot works totally fine, with either port - which is the most confusing part, I thought the port on the KVM might be bad.

I also tried another unit of the same model KVM, issue still exists.

Based on my deduction, it would have to be that Luxa just doesn't play well with the KVM, for whatever reason. It's using a Sapphire Vega 56, so no slouch on graphics either. Again, it does work perfectly fine directly to the monitor, and it works fine with MechBot (using an MSI RTX 2080S)
I personally cannot fathom why Luxa or the Vega 56 would not play well with the KVM, but that's the best deduction I could reach - I am obviously looking to fix it though or get some insight and curious on additional opinions

Thank you for your time

~ Trip


Possible what you've deduced is true. I've had a system that only presented purple, green and white artifacting only when in BIOS or when the OS was loading(the dots circling) only one TV/panel out of nearly 24 panels in an office I'd given support to. I tried a BIOS update for the platform and then went through the TV's firmware to see if anything was pending. Nothing happened until I got a call from client stating that the panel that had given the artifcating was dead, the daughter board on the TV was corrupt. A closer inspection of the board showed that it'd suffered from a lightning surge/strike whereby a capacitor was burnt out.

Not stating that your switch might be faulty or the panel itself, but it's a good idea to rule out all options before putting the nail in for good.

Check to see if the BIOS is updated(gradually work you way to the latest version) and that the OS on both, Windows 10 are on the latest version as well, ideally 21H1. Got a link to the KVM switch? Swapped out cables for the KWM on the inputs?
Apr 6, 2021
Hi, thanks for the input! This is the link to the KVM. BIOS is updated, and I have tried 4 different cables. I initially thought it to be something with drivers, but there's no way it can be a software or driver issue if it happens pre boot, during the bios.

That's an interesting story - it worked fine on all 24 panels but one?
Over here the thing is, the monitor works just fine when connected directly. The only thing I haven't tried is swapping the monitor cable to HBM3, I'll try that tonight.

Interestingly, others have mentioned this problem in the reviews as well, so maybe that's telling. Possibly it works fine with NVIDIA and not AMD