Some detailed questions about the Level1 KVM

Hardware
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So the (restocked soon?? pls?) Level1 KVM supports 4k @ 60hz, and I am given to understand it will support higher framerates at lower resolutions.

Is there any way to know (other than testing it) whether it will support 3840 x 1600 @ 75hz?

I just bought a monitor with this spec and it would be nice to get the full refresh rate if possible.

On another note, and I apologize if this has been covered elsewhere, but has there been any testing on how much input lag the KVM introduces?

The secondary computer that will be attached to this is a USB-C macbook pro, curious to hear of others have tried this. I’ll be connecting the MBP to a USB-C dock, and from there connecting the dock to the KVM.

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Yes. I don’t remember the exact list, but I believe it’s whatever DisplayPort 1.2 supports

I’m not sure. Have you read through the announcement thread for it? There’s a lot of good info in there. (linked below)

No testing, but it shouldn’t introduce any. It’s just passing on the USB signal. Think of it as a hub. If there is any, it may be 1-2ms.

People have reported difficulties with certain USB-C to DP adapters, but you’ll have to ask about the specific dock. Again, this has been somewhat covered in the thread linked below.

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Thanks for pointing me to that, @SgtAwesomesauce.

So after looking into it, it appears that 3840x1600 @ 75hz is within the spec for DP 1.2, although close to the limit.

As for usb-c MacBook pro use, it seems that the jury is still out on that? @dipth were you ever able to get this working?

@wendell have you had any experience using the usb-c MBP’s with the kvm?

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I’ve been using the KVM with an LG 3840x1600 monitor for awhile now, no issues.

Dunno if you’ll be able to get 75 Hz working in macOS though. I have a Hackintosh VM setup and 75Hz doesn’t work properly with an AMD card in macOS, it frameskips. Has nothing to do with the KVM, even directly connected it exhibits the same issue. I tested it on High Sierra so there’s a chance this is fixed in Mojave though. Could be because macOS doesn’t support FreeSync (to my knowledge anyway).

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It is somewhat hard to get a good USB c to dp connection on Macs. Several users report success. Several report problems.

Some of the worst tickets we’ve had have been from Mac folks. The expensive thunderbolt docks seem to work best but the display port passthrough seems most troublesome. I’ve had good luck with non Mac USBC devices when using shorter cables or active adapters.

60hz really is the upper limit for 4k. You can kinda sorta get 75hz on the leftover bandwidth of the true Max of 4096x2304 but in practice it’s impossible. Kvm has no active repeater.

The cabling situation can be super super picky too. This kvm is a good as it gets, but it’s also not perfect.

Alternatives if it doesn’t work are $100 do repeaters or $200-$400 high end thunderbolt docks. The docks generally are awesome anyway because multi display and all that… But Mac people far and away have been the most complaints. And I’ve bought some Macs to try to work out the issues but it’s mostly out of spec dp signals I can’t do much with.

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Can confirm. It has been problematic with my Thunderbolt 2 Macbook Air and Belkin Thunderbolt (first gen) dock, but works great with “real” computers.

Also can confirm. Even using DP 1.4 cables, running them too close to a bunch of power cables caused intermittent connectivity problems. Problem went away after cable management was fixed.

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@wendell the resolution is 3840x1600, not 4k. It’s within the bandwidth limit of DP 1.2 even at 75hz, so it should be ok.

My plan is to connect the MBP to a USB-C based dock such as this:

Then from there to the kvm.

Sounds like it is at least worth a shot. I’m not playing games on the MBP so I can dial down the refresh if needed, as long as I get 75hz from my desktop (dual booting windows and Linux)

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On a seperate note, has anyone tried tying it to a thinkpad ultradock? Do all the ports passthrough correctly in linux and windows? Asking for a friend who recently acquired far too many thinkpads. I believe the 20 series motherboards do dp 1.2 https://forums.lenovo.com/t5/ThinkPad-T400-T500-and-newer-T/T520-DisplayPort-version/td-p/1340905. Wondering if the dock is one too many daisy chains.

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If you do this, please post here with results. It would be great to have a list of confirmed TB docks that work with the KVM.

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@oO.o Will do! It won’t be for awhile though.

Already I discovered that the caldigit unit only does 4k at 30 hz, so I’m looking elsewhere. The Dell d6000 seems to be a good option at the moment.

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I have used the dell docks but only the newer ones with newest firmware work well. They appear to be “quietly” replacing old buggy tb docks with new ones with a newer chipset. I encountered this also.

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Usb-C is a giant mess. I’ve had so many problems.

From what I can tell, the d6000 is the newest one from dell - hopefully the best option?

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Just got my KVM today, and I’m running into some issues (surprise!) getting my old mac pro 2010 cheesegrater w/ vega working with the KVM. Does anyone have a recommendation for an EDID aware DP repeater that has been successful at 4k/60hz (pref. HDR)?