Big monitors with multiple computers
April 27, 2021 3:50 PM   Subscribe

Can anyone recommend a good KVM solution? I'd like to use a couple of big high-res monitors, keyboard and mouse with either my personal MacBook or my work MacBook.
posted by aeighty to Technology (10 answers total) 6 users marked this as a favorite
Best answer: I couldn't find a good, cost-effective solution for this use-case about 8 months ago, so I ended up buying a USB 3.0 switch (which allows me to switch the keyboard and mouse between up to four devices) and connecting different devices to different inputs (in my case, personal desktop gets DisplayPort, work laptop gets HDMI) on one of my monitors. That ends up being two buttons to change KVM (one to change where the keyboard/mouse are routed, one to change which display input is hot) but doesn't compromise on bandwidth for displays, which was more important to me.
posted by Alterscape at 3:59 PM on April 27, 2021 [2 favorites]

Do you require Thunderbolt 3 or 4 support, in order to connect 5k or 6k monitors (which require TB3, at a minimum)?

TB3/4 will complicate your KVM options considerably, as there are none that are commercially available, at the moment.

Feel free to follow up with a bit more detail about your setup, as that might help with usable recommendations.
posted by They sucked his brains out! at 4:15 PM on April 27, 2021

"a couple of big high-res monitors" isn't enough detail. Exact resolution and available monitor inputs would be useful. Or are you saying you haven't bought them yet?

Does this do what you need? That's switching for USB and two 3840x2160@60Hz HDMI connections. A$273.57 (Shipping: A$8.52, additional taxes may apply.)

Note that "dual 4k" via USB C will usually use the USB data lines for video, so you'll need a second port for USB. I couldn't speak to the latest latest ports on a Macbook.

Getting two video outputs and USB out of a Macbook almost certainly needs an adapter that borders on a dock. If you're not switching back and forth between the two devices during a session, you're probably just better off getting that dock and plugging in the one you intend to use at the time.
posted by krisjohn at 4:18 PM on April 27, 2021

Response by poster: I'm gonna stick with commonly available 28"/32" 4k monitors (I've yet to purchase them). I'd like to switch between work/personal setup seamlessly. I'm a coder so no requirements for high end color reproduction or super high fresh rate.
posted by aeighty at 4:20 PM on April 27, 2021

Do you need it to be controlled by a switch? With laptops I find it very convenient to use a dock like this thing and just plug the one cable into whichever laptop you want to use at the moment. (You can get it in HDMI or DisplayPort so decide which monitors you want first)
posted by aubilenon at 4:29 PM on April 27, 2021 [1 favorite]

Best answer: 2x1 KVMs will let you connect two computers to one keyboard, one mouse, and one display. You might want to look for a 2x2 KVM. This type lets you connect two computers to one keyboard, one mouse, and two displays ("2x2").

Here is a 2x2 KVM that supports two 4k displays at 60Hz over DisplayPort.

If your MBPs have USB-C, you might look for USB-C-to-DisplayPort cables that support the 4k resolution at the 60Hz refresh rate (example). If you have older MBPs, you might look at using a mini-DisplayPort-to-DisplayPort adapter.

Even if you don't do work related to video or gaming, a refresh rate lower than 60Hz will be noticeable and quickly get annoying. Cheaper 4k displays and KVMs can top out at supporting 4k at 30Hz, and this is often put into the fine print. So that may be one specification to carefully look for when shopping for displays and a matching KVM.
posted by They sucked his brains out! at 4:43 PM on April 27, 2021 [5 favorites]

Consider barrier, a virtual km switch over network, along with video input switching via monitor as suggested by Alterscape above.

As a bonus you could use it to jump over to a laptop’s built in display while using the other laptop on the big screen.

You can switch controlled computers with keyboard shortcut.

You will need a ‘server’ computer so one laptop always connected/on.
posted by soy bean at 8:09 PM on April 27, 2021

I don't bother with a KVM at all in this situation. I use a 4K TV as my monitor, which has multiple inputs so I use one for my personal device and one for my work. I use a bluetooth keyboard and mouse that can bond with multiple devices.
posted by Runes at 6:56 AM on April 28, 2021 [1 favorite]

I do a combination of what Runes and soy bean suggest. I have both my work *and* home laptop plugged in and running at the same time at home. One MacBook has two monitors, the other has one. Both run lid closed. I use the Logitech K380 keyboard which can connect to three Bluetooth devices; you switch with a single click of a button. Additionally, I have the Logitech M720 Triathlon mouse which can also be assigned to three different devices; switching is a simple button click on the mouse. However, using those built-in buttons to switch is really only backup because I use a software KVM solution, Synergy, which "barrier" linked above is based on. They allow one mouse and keyboard to be used across multiple desktops seamlessly over the network. The mouse moves across the two computers as if they are one and the keyboard is automatically active on whichever computer the mouse is visible. It also allows copy and paste between machines with about 0.75 second delay (meaning, you copy, wait about a second then move the cursor to the other machine to paste). It's nearly perfect; it sometimes lags if the host is maxing out its CPU, and occasionally it forgets where the cursor is so you have to wiggle it: both are also true for barrier and paid Synergy. (Logitech has software for software KVM that comes with the mouse but it was inelegant and less seamless.) Instead of paying for Synergy, use the open source version binaries built here:

If I take one of the computers or monitors out of the setup, the KVM software adjusts automatically.
posted by Mo Nickels at 12:20 PM on April 28, 2021

Response by poster: Thanks for everyone's suggestions. I do need an external hardware solution, my work laptop is pretty much locked down and is not eligible to run 3rd party daemons.
posted by aeighty at 4:11 PM on April 28, 2021

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