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The Level1Techs KVM (Keyboard, Video Mouse) Switch - 4k/60hz monitor & USB Switchbox | Level One Techs


#181

How long is the cable between the usb-c to displayport cable and the KVM? How long is the cable between the KVM and the display?

That resolution + refresh rate is pretty close to the max bandwidth supported by the KVM, and by displayport 1.2, and can also suffer if you have lower quality displayport cables.

I have a similar display ([email protected]), and connect it to both a Linux laptop and macbook via a thunderbolt 3 hub without issue, but I was pretty selective with my cables. From wendell:

A quick test to run would be to try it with shorter cables. I also have a USB-C to displayport standalone adapter, and found that it can struggle to work with same-length cables that would otherwise work, so you might also have to take that into account.


#182

Which adapters? can you link me on amazon so I can order one of them to test? I tried the club3d one and it seemed to work but I can test yours. I have a box I can send you for further diagnostics in case the signal coming out of there is weird if you’re up for some experimentation.


#183

The total cable length is something like:
Laptop to KVM: 1m
KVM to Monitor: 2m

The cable from the KVM to the monitor is a Displayport 1.4 cable rated for [email protected]

I have also tried lowering the resolution and refreshrate on the laptop all the way down to [email protected] which didn’t change anything.


#184

@wendell one of the adapters is this one:

https://www.av-cables.dk/usb-til-displayport-adapter/usb-c-3-1-til-displayport-adapter-4k-60hz-1.html

I have no idea if the adapter is available in other markets.

I can’t recall where I got the other one


#185

If there is any chance I can make this thing work, I’m up for any sort of experimentation :smiley:


#186

I am ordering one of these: https://www.amazon.com/DisplayPort-uni-Thunderbolt-MacBook-Pixelbook/dp/B07CL31FR6/ref=sr_1_fkmr0_2?ie=UTF8&qid=1529270946&sr=8-2-fkmr0&keywords=USB-C+3.1+til+Displayport+adapter+4K+-+60Hz – not sure I can get the precise one you linked, but I’ll keep digging around.

I will try this cable, and then go from there. May need to direct message you to arrange some of the more exotic testing. I have some “working fine” reports on 2017 mbp so there is something that works. I think the thunderbolt docks also work, in general.


#187

Sure, just let me know :slight_smile:


#188

DVI (or HDMI) to Display Port adapters are pricey and I need at least x2, I’m tempted to buy a cheap GPU in their place. Since I’m not a gamer, would an rx580 4gb be plenty to drive an LG 43" 43UD79-B 4K (3840 x 2160)? Or maybe 580 8gb and if I get the gaming bug just play at 1080p?

  • EDIT- HA! I forgot I have a 702084-001 (GTX-630 2GB) from a failed fold at home Ubuntu VM build (couldn’t get it to work right). It has two display port on the back. But I’m getting conflicting info, that it only supports 2048x1536, another says 2560x1600, yet another site says 3840x2160. Maybe Nvidia has updates for this card to get it to 3840x2160?

  • EDIT- slapped it in and heck, 3849x2160 and 100% scaling- cool. Was going to be $40.00 x3 for HDMI to DisplayPort adapters, I just need one now.

  • Edit 3, ran Heaven benchmark for fun on the poor little 630 on the 43" 4K. 2FPS lol.


#189

might want to check your refresh rate. is probably at 30fps


#190

Every time I switch between the desktop and laptop. the desktop’s (Win10) windows re-autosize into little squares at the top left of the screen I have have to drag them all out and re-size them again. Is this in relation to the PC thinking the screen was completely disconnected in the interim? Is this fixable if the KVM emulates some kind of signal to keep the PC happy?

I have a sneaky suspicion its the LG monitor trying to be smart (has firmware for all kinds of split screen modes etc) vs. being a passive monitor.


#191

Thats because the KVM disconnects the monitor from the computer. Its intended behavior


#192

This really deflates my experience with the KVM, was really hoping to be able to switch between laptop, work laptop and desktop without having to re-lay things out every time.

How do I do this on just the desktop? Lots of google results for gaming or GPU benchmark software, but how do I see what FPS I get just displaying the destkop?


#193

iirc just right click the desktop and select screen resolution. select your 4k monitor and click properties. should be in there somewhere


#194

Went into nvidia control panel, apparently it is at 60hz. Pretty happy because it was a ‘free’ part laying around from a craigslist z800 buy I use for an ESXi box.

This. When I switch back to the Ubuntu laptop, its as I left it. When I switch back to the Windows 10 desktop, everything is stuffed in the top left and the LG pink’ish screen outline comes on for a few seconds. Need to find a way to make the LG monitor dumb to the fact its a Win10 PC.


#195

This is a common complaint with KVMs that don’t emulate the screens. Windows in particular moves everything to a screen that’s available, and when there’s no screen available it doesn’t know what to do with itself. Linux, depending on the desktop manager, is sometimes a little smarter, and keeps the layout as is (I believe the area where windows are drawn is a separate concept from the screen where they are displayed, at least in desktop managers I’m used to, and it might actually be an X thing, so disconnecting and reconnecting a screen might not have an effect on where windows are).


#196

Will try some of the mentions found in the link-

I might like a software/setting work around more than a kvm with emulation, but we will see, the adventure resumes tonight.

@wendell, were you adverse to a kvm that emulates output due to cost? Complexity? The Belkin F1DN104W-3 at work doesn’t have the windows re-size and move, but they require a monitor power cycle sometimes and far from perfect, and cost WAY more- so I’m routing for a win10 or Nvidia hack to change this characteristic.


#197

On quadros for sure you can do it such that it isn’t removed.
It’s manual injection of edid.

A lot of early dp monitors report they are unplugged when they go to sleep too so there are a lot of work around because of that.


#198

So I do not have the menu in Nvidia control panel as its not a quadro- boo.

The persistent windows (app?) here: http://www.ninjacrab.com/persistent-windows/ seems to do the trick. I wish I understood how it worked (maybe a level1’er can break it down/explain it).


#199

@wendell a small update. I just got my hands on this adapter:

This one is listed as being compatible with the MacBook Pro 2017, but unfortunately the problem persists.


#200

I should also mention that I have tried an SMC reset and NVRAM reset as well without any luck