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KVM switch buying recommendations?

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BikeGremlin

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Putting this out, in case I get lucky (already tried specialized forums and similar).

I came across this Reddit post. It wonderfully explains some of the nunaces of HDMI vs Display connections for laptops and desktop monitors. Reddit is corporate-owned and stuff gets deleted, so I'll give myself the liberty to copy-paste the awesome post just in case:

There's no such thing as an HDMI to DisplayPort cable!​

Not one that actually works at least.

You can go from DisplayPort to HDMI, as DisplayPort can to output an HDMI signal. The cables are missing a single pin on the DisplayPort side which signals the hardware to output an HDMI signal instead of DisplayPort. This happens with zero lag, but you can't go the other way!

To go from HDMI to DisplayPort requires a powered adapter, usually a box with a short HDMI cable for input and USB cable for power. These will add some lag. How much? Who knows, most of these devices aren't going to have reviews from people who can test to find out, but likely no more than a frame. You also need to check what refresh rates the adapter supports, as many will likely be way less than what you're looking to get (most max out at 60hz), and good ones that do can be expensive.

Similarly, yes, most USB-C or Thunderbolt video outputs will add significant lag, more than an HDMI to DisplayPort adapter would, assuming your laptop has a discrete GPU. However! Most laptops will have that exact same lag on their other video out ports! So your HDMI port may already have the same added lag as using the USB-C port would! Even the laptop's own display may already have this lag!

The reason for this is there can only be one physical connection from the monitor to the laptop. For power usage, the most sensible option is to connect directly to the integrated GPU, the one in the CPU itself. This means when the laptop is in low power mode, the iGPU has direct access to the screen and the discrete GPU can be turned off. However in this setup for the dGPU to display things to the screen, or to otherwise output to any of the video outputs, the dGPU has to copy each completed frame back to the system RAM, and then get output by the iGPU.

Some gaming laptops will have what's called a MUX switch. In this case instead of the display being connected to the iGPU, it'll be connected to a bit of hardware that can switch between the output from the iGPU or dGPU, which removes that lag while preserving battery performance. It can also make dGPU battery usage slightly less as the iGPU can be turned off. Some higher end gaming laptops will also have the MUX switch attached to the video out, and USB-C. Finding out if your laptop has one or not can sometimes be hard to find, but Nvidia recently started advertising this features as "Advanced Optimus".

...

But, after that giant block of text lets go back to the main thing you're concerned about.

"DisplayPort ... gives more bandwidth (than hdmi)".

Sort of. The latest DisplayPort 2.1 is faster than HDMI 2.1, but almost nothing actually implements DisplayPort 2.1 yet with Nvidia GPUs not even supporting it, and there only two DP2.1 monitors on the market. So really the comparison is between DisplayPort 1.4 and HDMI 2.1, and HDMI 2.1 is faster.

But, many monitors use older, and slower, HDMI standards such that they can't run at their fastest refresh rates unless using DisplayPort. Especially those in the budget price range. The reason for this is fairly simple, DisplayPort doesn't require any licensing fees, but HDMI does, and the newer HDMI spec licenses cost more. So it's cheaper to not support them. So you may indeed need to use DisplayPort to get the max refresh rate.

However this may be moot, because depending on your laptop it may not be able to output that refresh rate either way. You need to check what refresh rates your laptops supports over HDMI. There's a good chance your laptop also does not support the latest HDMI standard, making an HDMI to DisplayPort adapter pointless as you'll be limited to the same refresh rate the monitor is already limited to over HDMI.

If your laptop's HDMI spec is limited to less than HDMI 2.0, you'll need to see if it supports DisplayPort Alt-Mode (aka, DisplayPort over USB-C) at all, as not all laptops do even if it does have a USB-C ports. The port itself should have either a DP logo, or a Thunderbolt logo. If it does not, you'll need to check the laptop's manual. And after that you still need to check what resolutions and refresh rates are supported over USB-C, because it may still be limited to similar refresh rates as HDMI.

...

TLDR: Read all of the above, or just stick with HDMI.

That post is awesome, though it is a tangent to what this post is about. I'm looking for a good quality KVM switch.
As far as I know, many (most?) IT professionals don't even know what that is, with "everything" being Internet-connected nowadays, but I run some stuff offline and still prefer to use one keyboard and mouse for controlling several computers (no cluttered desk, more ergonomy).

My current setup​

My current, well over a decade old KVM switch is Digitus DC 12202 USB-PS/2 COMBO KVM Switch (Amazon.de affiliate link). It's getting long in the tooth. Every couple of days I need to unplug the cables to make it start running again (when it gets stuck and won't switch computers). It only has VGA connectors. To connect a modern PC, I must use a VGA-HDMI adapter (that's the one I'm using). That's not very practical, since any computer from this decade no longer comes with a VGA output (the same goes for both laptops, and desktops).

What I'm looking for​

With all above-stated in mind, I'm looking for a good quality (reliable) KVM switch with HDMI 2.0 display ports, for connecting up to 4 computers to one set of keyboard + mouse + monitor. Ideally, it should support a 4K resolution @ 60 FPS.

It will be used for work, so lag is not really an issue. The same goes for how fast it can switch (I can wait for several seconds if needed).

Ideally, it should work with mechanical keyboards and mice sold today as "gaming" (apparently, there's no other way to get high quality mice without paying an arm and a leg). Having said that, it needn't transfer any fancy combos or controls - I just need the two mouse buttons, scroll wheel, and keyboard to work for typing.

I can only buy stuff from EU and Serbia - that is a limiting factor, but that's how it is.

Budget?​

I'm willing to pay for durability and reliability. I understand that it costs a lot nowadays. Ideally, I'd like to spend less than $100, but if $500 or more is needed to get a durable solution, I'd be willing to spend even that much (not a small amount for me).

Final notes​

Please recommend stuff that you've personally tried and been happy with. Reveiws are very hit-and-miss (if you know of a truly reliable IT review site or YouTube channel, please let me know). Thanks in advance for any help or advice.

Relja
 
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Turns out I got some promising feedback. These two models came highly recommended:
Both switches support EDID (Extended Display Identification Data). Why EDID matters?
  1. Maintains Display Settings: With EDID, the KVM switch reads and retains monitor data like resolution, refresh rate, and color profile. This avoids display glitches (such as incorrect resolution or refresh rate) when switching between computers.
  2. Improves Stability: High-quality KVM switches use EDID to prevent monitor flickering or black screens during the switch by ensuring the active system continuously receives the display data.
  3. Persistent EDID Emulation: Advanced KVM switches have EDID emulation, where the switch "mimics" a display’s EDID to every connected computer. This keeps the settings stable, even when the display or KVM switch is off or changed (otherwise, your PC might set its display to a low default resolution when you switch from it to another PC, since it would "think" that its display has been disconnected).

Out of the two, StarTech came with more very high first-hand experience recommendations.

ATEN does also have a good reputation (and user reviews) generally. It is cheaper (comparing the two 4-PC switches), and it comes with a full set of needed cables (unlike StarTech for which I'd have to buy cables separately, from different manufacturers/suppliers).

So, with decent-quality cables, the price difference is pretty large, well over $300! ATEN comes at around $400 with cables included, while StarTech is over $650 with no cables.

Tough choice, though as far as I can tell based on the recommendations, either of the two will get the job done and work fine. I'll definitely sleep on it (NO, not the switch dammit! :) ).
 
There are a lot of new things to learn - I didn't even know about the existence of such devices :unsure:
But you are a meticulous person and I am sure you will make the right choice for yourself ;)
 
There are a lot of new things to learn - I didn't even know about the existence of such devices :unsure:
But you are a meticulous person and I am sure you will make the right choice for yourself ;)

Thanks. :)

Yes, they used to be a lot more popular "back in the day." Over the last decade, it has all become connected so most people just use virtual connections (tunnels, virtual desktops etc.), but for my use case, I still need to run computers on physically separated networks that must not be interconnected, and my existing KVM Switch is now very, very old (and has not Display port or HDMI connectors).

Don't like the current prices, but I hope the new one should work for at least 10 years (knock on wood). :)
 

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