[SOLVED] KVM Help (loosing my mind here)

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I’m running the LVL1Tech’s KVM. It’s worked like a top for several years now. But all of a sudden I’m getting random drop outs of 2nd monitor (I have the dual monitor one) SQ2625416 (DP 1.2)

i’ve swapped monitors around, using either high quality (supposedly) cables as well as dell default. All of these cables have worked like a top since 2019, even a newer longer set (which I’ve pulled out of the loop to validate). It does seem to be my “right monitor” with weird issues with MFT (I’m using a USBC dock for my work and *nix laptops).

I have the same issue on my linux workstation with the same no display port signal as I do with my Windows workstation. (hence the two 1080’s 1each) Windows started after 20h2 update but now I’m getting the same issue on both.

one odd behaviour, my win10 workstation will occasionally work, then sleep and then only report black screens even after reboot, on multiple graphics cards (including Quatro’s) a gtx1060, as well as onboard Intel graphics. so reboot reports black screen continuously.

On both linux wkstn and laptop I will regularly get a single monitor to display ( R monitor).

Various generation quatro’s used, gtx1060, 2x1080’s, onboard intel graphics. Linux, BSD, and Win10.

The oddest thing is my Win10 work laptop will display both monitors correctly 90% of the time through the same USB c dock, $60 cable matters.

The key to all of this, this has worked flawlessly for 2 years with the same cables (I’ve removed new cables to validate) Multiple OSes, etc.

Sorry for the rambling this is a note dump and I’ll add more troubleshooting (direct connect to monitors next)

details and individual systems tested
SQ2625416 - DP 1.2 dual monitor KVM
Intel 6700k + 1080 + asus sabertooth
LG Gram (2021) + cable matters usb c dock
Dell lattitude 5400 + cable matters usb c dock
Chinese franken dual xeon + 1080
Dell 7010
Razer egpu enclosure + 1060 connected to LG gram

Unfortunately this is killing me as my VM’s were on vmware workstation on the win10 machine for a security class I’m running through and I’m also working 70hrs a week doing security and need to get these all working (KVM is essential lest I have 50 monitors and 10 keyboards)

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direct connect to monitors through USB c dock now shows the inverse. on the Right is now not working (where it was before, if I confused that before sorry).

MFT off and it stops working. Switch cables ports, changes monitor, multiple cables same.

OK so usb-c dock is probably toast. so I’ll move on from that and look at the desktops.

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direct connect to PC with known good (though longer cables) blank screen. unplugging monitors and waiting to see what happens with a reset.

4

PC reboots black screen, monitors still show (no display port signal detected)

I guess I’m going to try an HDMI cable next to see if this continues.

5

HDMI black screen on PC. Moving to reset bios. monitors work individually on other devices.

so I’m going to get this pc connecting and rule out some of that and then come back to the KVM.

But kvm issues REcap:

often cuts out one monitor showing “no signal”. systems going to sleep will often induce this and happens with MFT on or off.
happens with multiple cables, gpu’s, and systems.

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you might try some ferrite beads since it was working but then stopped. probably external interference from something else.

did you get the 1080 firmware update? google nvidia display port firmware update. its also possible if you didnt get the FW update the issue didnt trigger till newer video drivers from nvidia.

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Thanks, I’ll check that. I’m not sure if I got the new DP update for those but that could explain it since all quatro are older and they’re all 10 series.

You’re thinking it’s maybe a windows + monitor firmware update? (FYI dell 27" ultrasharp)

I don’t have any ferrite beads handy but I could see if my old CRT’s have any and are easy to pry off.

I’ve always done the driver updates for the 1080’s, any thought on the specific DP update for that? I’ll google but might be a good idea to pin the link here for others who are searching.

  • cheers
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https://www.nvidia.com/en-us/drivers/nv-uefi-update-x64/

Link for others.

So, I had setup my Corsair h110i to show red if temp got too nuts. as I was playing with all of this it would occasionally show that. Pulled it off and the cpu needed to be repasted.

I’m also leaning towards the odd mix of issues being the display port update issue for the 10 series cards and I’ll be investigating that after stepping away from throwing my pc out the window.

Got pc to boot after unplugging and resetting cmos and repaste, shuffled the ram around and did a memory test (all good).

only using onboard graphics at the moment to get into windows and then I’ll update the 10 series cards and validate those.

after the break I’ll get back to seeing why the LG Gram and win10 dell wouldn’t connect on the monitor, so I’ll be validating monitor firmware as well.

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ok… so far there appears to be a confluence of issues.

  1. Win10 PC - 6700k + 1080 = g2g (repaste cpu, reset bios) now it’s working. Found that the nicer end cables were a little too wide to use with the strix 1080 and might have been causing the random 1 monitor drop out for that pc.

  2. work dell + cable matters cheapo dock works great, seems the win10pc was causing monitors to report no signal and would intermittent kick off (re:cable plug dimension not great on win10pc)

  3. lg gram not working on cable matters dock, seems more related to kernel upgrade and updates which might explain why it’s no longer working with the razer egpu dock

  4. linux wkst working fine (pictured here).

I’m going to check the Display Port firmware as there were some other wonky cut outs before. I threw away the non VESA cables but I wasn’t using those on the recent setup either.

I might look at getting the LVL1 repeaters but at $100 a pop they will be too much for every machine but a set to test from and easily do external capture will be nice.

I’ll report back more info, but really odd behaviour where one failed machine causes a cascade of the others (sans LG Gram, that’s likely Ubuntu being Ubuntu).

  • Cheers
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IMG_20210525_133024
IMG_20210525_1330244608×2176 2.66 MB

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I’d get club3d 1 meter cables to use where possible before the repeater. And maybe a strategically placed ferrite bead or two

2 Likes
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all working like a top right now. But I’ll be swapping out the longer cables. I’ve got a box of Dell supplied cables at work and will try those. They’re just shy of 1 meter.

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DP 1.4 upgrade seems to have addressed the ghosts as well. Cheers mate! @wendell

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I might have done this. Oh. Once or twice. Be me, in product development for this, have a tac open with Nvidia pointing out flaws. Be them sayings it’s fine. Be me going back to the drawing board.

Then 6 months later fw update. I’ll drink to that!

1 Like
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It explains why running Hash cat on the main GPU causes artifacts and random DP resets. … well it doesn’t explain why it would do that but not noticing it anymore.

Enjoy your Orange Crush. :smiley:

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