L1 KVM cable lengths

Level1 Store KVM Helpdesk
1

Hey everyone,

My L1 KVM arrived today (DP 1.4, single monitor / two PC / 10Gb) :grinning:, using Club3D cables bought from a reputable retailer it looks like I can get my PG27AQN working at 360Hz when I go…
PC > 2m cable > KVM > 1m cable > Monitor

Yet when I swap the cables and go…
PC > 1m cable > KVM > 2m cable > Monitor, I top out at 240Hz before a blank screen.

I’m just curious, is there a technical reason for this given the KVM is just a switch that doesn’t have any sort of repeater in it? Typically I would ideally need the longer run to be on the monitor end for my desk setup!

Does anyone have any general experience with the L1 KVMs and the PG27AQN running reliably at 360Hz? I appreciate this is right on the bleeding edge, but if anyone can confirm it runs OK for them I don’t mind investing in the FIBBR cables if I have to. The PC has an RTX 2070 Super in if that makes any difference running 532.03?

:::edit::: well after a bit of further testing it seems to be shitting the bed and flashing a blank screen periodically even at 240Hz (1440p) with the cables either way round :slightly_frowning_face:

2

Yeah there was a bad batch of club3d cables in Germany too.

Give the 2 meter fibbr cables a try and I bet it clears up.

1 Like
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Cheers for the reply wendell, have you guys had chance to test the KVM with the PG27AQN?

I can confirm each of the Club3D cables works perfectly on its own at 360Hz, I’ll get a FIBBR cable ordered to have a play with and see if that works :slightly_smiling_face:

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yeah other reports from other users of that display working just fine. the kvm is really too stupid.

yeah so since the kvm tries to be invisible even though each cable works fine on its own its really not useful for testing except to rule out you have a heinously bad cable because the losses through both cables (and the kvm) are combined … what your gpu sees is the combined signal loss / one long signal corridor of the cables on both sides of the kvm, plus the kvm. generally keeping the total length of copper on the order of 2 meters from gpu to display is a good strategy… but not always.

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Nice one, 2x FIBBR cables on order :slightly_smiling_face:

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Make sure it’s not the 3 foot ones. Some reports of issues with those too

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I ordered 2x 2m for a bit more flexablilty than 1m + 2m, sounds like that was the right choice!

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Quick update on this, my 2m FIBBR cables turned up today and so far its looking promising!

Not too much time testing it just yet but I’ve not had a single black screen/glitch yet :+1:

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Great! Going to add you to the FAQ :smiley:

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Hi Amber, just before you do that over the past few days testing I’ve started to experience screen blackouts again unfortunately. The FIBBR cables appeared to work initially, but after a day or so for whatever reason the problem has reappeared.
I can’t understand why that would be the case as its not like I’ve been rough with the cables or anything. As this is my first experience with optical displayport cables and I’m not familiar with how robust they are I’ve been extremely gentle and careful not to mis-handle them.

I’ve tried every combination Club3D/FIBBR cable layouts I have available, different monitor firmware versions, different displayport ports on my GPU, even a brand new GPU as I’ve just done an upgrade - having the KVM in the chain is the only constant where issues arrise.

I’m at a bit of a loss what to try now, I’ve even had the odd dropout (though only one or two) when running at 240Hz/1440p. Its always the same issue of a black screen for a moment, no distortion or flashing or anything like that before the signal drops it just dies for a second or so and then is fine for a little while :slightly_frowning_face:

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Given the lack of replies I guess I’ve bought an expensive USB switch.

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Oh I’m sorry! I didn’t see your replies. I wasn’t trying to ignore ya

You should totally see if you can get an RMA from Wendell. Email him at wendell at level1techs dot com

We’ll test the new KVM before we send it to you :slight_smile:

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Unplug your monitor from power for one min then plug back in. Bet that fixes it.

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Hey Amber, no worries.
I’d rather get it working if at all possible as I’m overseas from you guys so RMA would be a bit of a PITA for all involved :slightly_frowning_face:

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Ah I understand. Is there a status update?

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Thanks for the reply Wendell :slight_smile:

I can confirm this doesn’t seem to have made any noticable difference. Does the order of powering things on matter? If so I assume it’d be KVM on first, then everything else?

Interestingly the issue seems to be worse in game than it is sat idle at the desktop for some reason, then when I drop back to the desktop I only get the occasional hiccup again - both game and desktop are set to 360Hz.

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Hmm, very interesting. Try disabling freesync/gsync in the monitor OSD. Does that make a difference? Wonder if something is causing more of a clock skew somewhere than I expected

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Yeah I wondered that, I have ULMB on but thats all - I can try it without?

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Any update trying without?

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Hi Amber, sorry about the glacial reply - I don’t log in here very often.

Unfortunately the KVM doesn’t seem able to do reliable displayport switching in my setup, even after spending the additional on optical cables. 144Hz doesn’t seem to be too unreliable, but if I’m honest I haven’t done much testing with that as if I’m not able to use the 240/360Hz capability of my monitor there’s not much point.
Given my monitor has a G-Sync module, I’m not able to disable any of the features like adaptive sync on the monitor, only in the nVidia control panel, which doesn’t seem to make any difference.
I’m currently only able to use it for USB switching, though even then as the HID ports don’t have enough current to power on my Wooting 60HE I’m not able to use the remote switching with it either. Its a bit of a disaster ha :rofl: