KVM Switch that works


I am using a KVM switch to switch mouse/keyboard/HDMI/USB to a common setup, where I have 3 monitors (1 HDMI via KVM, 2 other HDMI via USB->HDMI, but USB routed through HDMI)

It works, but sometimes looses sync, so the monitors realign for 10 seconds. it’s getting to be annoying

I am using this KVM:

HDMI KVM Switch (tesmart.com)

Anyone got something that just works, no hazzles?

I’ve always had issues with KVM switches, so I’ve specifically avoided using them when I’m setting up a desk.

I’m not sure if this would help, but my pseudo-KVM setup when working with multiple computers is that I have monitors that have multiple inputs (most of mine have 3 inputs: typically 2 HDMIs and 1 DP) and I have Logitech keyboards and mice that connect to multiple Unifying dongles. That way, it’s only a few buttons to switch between computers. This also gives me the option of switching the monitors independently. (Also, for reference, I have the Logitech MX Master series. And also, Logitech has a software that allows your K&M to move from one channel to the next seamlessly, but I haven’t played with it myself.)

@kvk I held off from commenting because I don’t have a kvm to recommend. But as there hasn’t been a deluge of kvm recommendations I will let you know two things.

Firstly, I have 2 monitors and 2 PCs. I have Bluetooth mouse and keyboard that I switch between each PC with a button press on each.

Secondly, my keyboard hadn’t been a personal project, I would probably have followed some advice from the embedded.fm slack group where several people suggested https://github.com/debauchee/barrier. Without knowing your specific setup / needs (I wasn’t able to fully visualise from your description) I can’t tell if it will be useful to you but it is definitely worth a look. It really seems like magic for a multiple monitor, multiple PC setup. Maybe it doesn’t fix the video requirement though.

I stopped KVM’ing when the number & types of connectors for monitors got out of hand.

I used Synergy, the more complicated alternative to Barrier as linked above to good effect in the past but not anymore.

I have three computers on my desk:

iMac with second monitor
Win10 standalone
Second monitor has three cables for DP (iMac), VGA and HDMI for the Pi.

The Pi has a wireless keyboard on a dongle. The keyboard is on top of the Win10 keyboard out the way. This and the monitor connection is when I have to interact with it directly.

The iMac, main machine, has an Apple wireless keyboard + mouse.

The Win10 machine (my previous iMac) has a shortened keyboard + mouse pushed under the display and is only pulled out when I have to interact with it directly.

I have more Virtual Machines both on the iMac and on the two ESXi servers than I want to think about.

Most of my work is on my iMac and I use VNC / MS Remote Desktop / VMware Fusion (as a client) to access other machines, real or otherwise, to push buttons. If I just need to see the command line, then ssh in. This works very very well for me. As I said, if required the real Win10 or Pi can be very quickly accessed.

The first thing I do with any Windows only config is figure out how to do it on my Mac. I’m not anti-Windows as such, but having one OS to lug around as a laptop is preferable. For instance, I’ve updated my Microchip LoRaWAN Stack code base this week, mostly using Microchip Studio and then copied the files over to my iMac, adjusted the autogenerated Make file and I’m good to go. I may try moving it to CLion as I’m trying to consolidate all the IDEs.

Hopefully this is food for thought, even if it’s not a KVM recommendation. Although I’d say as the signals are pretty heavy duty, buy a decent (aka expensive) one that you can try out and return - Amazon for the win here.

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I found that adding EDID pass-through connectors on the monitor cables helped my auxiliary computers think they were still connected to a monitor, so the switching time is much better. I ended up getting a separate HDMI switch and USB switch. The HDMI is a 2x4 and the USB is 1x4.

Synergy is absolute magic. I have a 3-monitor Windows setup, with a MacBook on the desk. Synergy allows me to use one mouse to move between them as if they were one screen. Copy-paste works, too. No button-pressing required for any switching operations.

But I don’t think this is what Klaus is looking for.

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Which Bluetooth mouse are you using? I’ve found that my Bluetooth mice tend to have a wake-up lag that gets annoying.

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Logitech MX Anywhere 2. Not sure whether you will think it’s fast enough but I have no complaints. My main BT lag comes from my 9 year old Surface Pro 2, not the mouse! Much faster on the work PC.

That’s right

I work for two clients, where they provide 2 individual laptops. I also have my own laptor, so that’s 3 computers

I have 3 monitors, one monitor that copies that of the laptop (HDMI out), 2 other monitors that are supplied from 2 USB to HDMI adapters.
All this is attached to the KVM box, along with mouse and keyboard

So I am using the KVM to context switch between the laptops. Since it is client computers, I am not allowed to install any SW

The KVM switch I have should have that added in the box. At least that’s what they stated, but when I do context switching, it jumps all over the place, so it seems not to work. I might try to buy some externals EDID connectors, so thanks for the suggestion

Wouldn’t that mean you need to manually need to set monitor HDMI input selection each time you switch?

I probably switch 20-30 times a day, so that would be time consuming

Yes, that’s correct. It’s only a few clicks on my monitors. What I end up doing is if I’m switching that often, I will leave one monitor always on my main machine and the other monitor always on the development machine, and only switch over the Keyboard and Mouse.

I also have the MX Anywhere 2 and the MX Master 3. The BT lag is non-existent if I’m using the mouse all the time (PCB layout, gaming, etc.). The main lag is when I haven’t touched the mouse for a few minutes (chatting, coding, writing documents). It will take a good 2 seconds to respond. The funny thing is that the mouse is definitely still awake, as it records my movement correctly, but the lag breaks up my flow enough that I switch to Unifying when I can.

Also, by using Unifying rather than BT, I can just move the dongle between computers, rather than trying to re-pair for a new computer. This was really handy when I had a bunch of Raspberry Pis to work on at the same time.

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I agree with everyone that the MX Master series is awesome, and Logitech Flow is cool, and I like Synergy also, and none of that really helps you.

I use this switch (desktop, laptop, and one set of cables to tap-in a Raspberry Pi when the need arises), which has worked smoothly for me with two caveats: https://smile.amazon.com/gp/product/B08NP3GZX7/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

  1. CABLES. And in particular, run length. Best I can tell looking at chips on the board in this KVM, and I bet this is common, it has a high-speed SWITCH, but NO re-drivers or signal conditioning or anything like that. This really bit me because my desktop is on the other side of my workbench, and optimum cable management calls for a 10ft cable desktop>switch, then the 3ft cable switch>monitor. That resulted in EXTREMELY borderline signal integrity. It’d work reliably with two 3ft cables instead if I put the machine close on my desk, but I went through a handful of 10ft cables before I found one that worked reliably.
    That said, my monitor is 4k60, so I’m really stressing bandwidth and SI here. It’d definitely be less hairy at a lower resolution (which I did verify with a 1080p monitor while testing)

  2. I’m not sure if this is the fault of the switch, or the fault of the TB3 dock I use with my Mac, or the fault of the mac, or what exactly - I suspect the Mac’s GPU drivers - but every so often, responsiveness on the external monitor drops off a cliff, like suddenly it’s only running at 20fps. I reset the system by turning off the KVM switch, waiting for everything to switch back to the Mac’s internal display, then turn the KVM back on again. Back to full 60fps responsiveness.