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Comment by LoganDark | Hacker News Reader

Are there any good KVMs for gaming? Right now, I use a capture card for video, connect the mouse directly to the destination, and use a piece of software called Deskflow to transmit my keyboard. But Deskflow occasionally crashes, so it'd be nice to have a hardware solution (also that can be used for BIOS/etc). And Deskflow also won't work if I install SteamOS, once Nvidia works.

I looked at making a solution myself, but for some reason, simulating a USB client device in software is extremely annoying, and requires specialized hardware that is also very expensive. So at that point, why not just get a KVM...

I frequently switch between 1080p and 4K for gaming since I don't like resampling artifacts. Never found a KVM that can handle 4K properly even for productivity. The mistake can be as basic as assuming a 100% scale factor.

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https://www.store.level1techs.com/products/kvm do some that might be suitable, they produce some of the highest end desktop-spec KVMs I know of. They're not cheap though.

Why are these so expensive?

They were engineered from scratch to work properly. They were some of the first of their type.

cumulative development man-hour divided by total production number is why

Why do you need to use a KVM rather than Sunshine+Moonlight? That's pretty much the gold standard for remote gaming.

The practical answer for right now is that I don't want software screen capture, but it also does not do any of the things I wanted to be able to do by having remote inputs directed to the hardware rather than simulated in software. Namely it requires software installation on the server, which means OS support becomes a thing, you can't use it in BIOS/firmware, etc.

Sunshine works on linux and windows, screen capture uses parts of the gpu meant to do that as result you get lower latency than separate capture and encode.

KVM is useful for when you need to be able to control earlier stuff in the boot process too, or even simple stuff like entering the password for full-disk encryption, or choosing a boot entry in GRUB, or changing BIOS settings... Many use cases for KVM and remote KVM.

Windows behaves badly during screen capture. I don't care if the gpu has a dedicated encoder and it is absolutely not lower latency than the gpu's native display output.

> Windows behaves badly during screen capture

How? I and many other have been using it for years without problems.

> it is absolutely not lower latency than the gpu's native display output.

and subsequent encode

If you're like playing Apex/Valorant/PUBG/Dota and such, and scared that use of remote plays might get flagged, you could just use HDMI-in MPEGTS-out Ethernet capture streamer building scale HDMI extender thing(I don't know the actual categorical name). Inputs can be handled by a separate device, or just wireless keyboard/mouse.

Note that if anti-cheat is a concern, common dev boards like Arduino Leonardo and Pi Pico could also trigger flagging, so maybe that needs to be done slightly differently too(assuming the intent is good and this don't count towards anti-cheat evading in whatever you're doing).

Good point, I do play some games with anti-cheat like ARC Raiders. I don't think software screen capture would necessarily be an anti-cheat issue, maybe software mouse inputs are more likely to be.

As for dev boards, it wouldn't ever show up as a dev board to the PC, it would simply be simulating a dumb hardware keyboard. That's one of the reasons I wanted the board itself to have its own wired network.

Perhaps one wishes to remote KVM consoles.

KVMs are for rebooting and recovering servers without needing physical access. Maybe you would have some chance with HDMI splitter connected with an EDID dummy plug and an HDMI-Ethernet capture encoder thing, and some dedicated KVM for just keyboard and mouse, but idk.

For me, I want to access my physical desktop without having to keep a physically separate monitor and keyboard than my MacBook. I have the physically separate monitor and keyboard, and I actually kept it co-located with my laptop for the longest time, but it's just more convenient to not have to swap it out with the laptop to maintain good posture, etc. (I use the laptop in bed due to chronic pain/disability)

Honestly, this whole KVM thread is a bit confusing to me. I've always equated KVM with keyboard/video/mouse switches: enabling multiple computers to be controlled by the same I/O devices. Nowadays I just use a multi-source monitor and USB switch for that (can even automatically control the monitor via DCC, depending on the switch state, look it up on HN).

And I usually refer to the "IP KVMs" as a "lights-out" module/engine as I was familiar with HP's "ilo (integrated lights out) [0]. More on lights out management on Wikipedia: https://en.wikipedia.org/wiki/Out-of-band_management

I was thinking of making my own with an ESP32 + serial, as that's enough in theory, though I am unsure how well-supported serial ports are in BIOS and bootloader. Also, IIRC RS232 is ±12V, so the ESP would need a level shifter.

TFA's device looks cheap enough (well, depending on shipping to EU), I may just get one. The screen is a bit superfluous though, and I think that the ATX power button support is a must.

[0] https://en.wikipedia.org/wiki/HPE_Integrated_Lights-Out

The whole situation around low-end server KVMs are a bit unfortunate IMO. BIOS can theoretically work with UART just fine, and not even full VGA@24bpp should be an absolute necessity for just confirming BSoD to decide to power cycle the machine, so it should be theoretically possible to be cheapened out a lot more to be e.g. telnet only or up to 5fps QVGA through HDMI-Composite adapter, or it could even be like a servo pointing an antenna to switch between different dummy load terminated VGA cables relying on TEMPEST techniques to get frames, for more potential cost and reliability gains.

I expected that kind of potato IP-KVMs to surface from crypto mining space, but alas, what we got was this thing which predecessor have reputation of crashing. That might not be stupid, but a bit frustrating.

> simulating a USB client device ... requires specialized hardware that is also very expensive

Pretty much any off-the-shelf SBC can present itself as a USB HID device like a keyboard. You can buy a very capable rp2040-based board for <$5.

What part of this equation requires expensive hardware?

The part where I want wired ethernet to that SBC, not some funky proprietary wireless chip as in ESP32. I almost found a solution, but I've been unable to get my picoprobe to properly flash and reset the board for some reason, so I haven't been able to use it for development. I'll have to troubleshoot that again sometime if I enter another bout of caring.

> The part where I want wired ethernet to that SBC,

In that case the path of least resistance becomes something like a $22 NanoPi NEO (has onboard ethernet, widely used in PiKVM setups)

Oh, you were talking about SBC, not embedded. I even echoed it, should've noticed. Whoops.

Maybe I'll look into that, wouldn't require messing around with the picoprobe. Thanks!

I don't really understand your setup, but if you throw enough money at ATEN they will be happy to give you a KVM that handles 4K @ 240Hz. Supporting high refresh rates is the main thing that would keep me from using most KVMs for gaming.

Ah, I neglected to mention that my keyboard isn't separate hardware. I'm using the built-in keyboard and display of my laptop, and would like to continue doing so. So hardware switches that depend on dumb monitors and keyboards don't work for me (and that's why I said KVM, not switch).

Most KVMs that fail at 4K get the EDID wrong. They either send their own fixed one (often maxing out at 1080p or 4K30), or they reconnect the display on every switch, so the OS thinks it's a new monitor and resets your scaling. Look for one with EDID emulation.

For high refresh 4K you also need HDMI 2.1 or DisplayPort with DSC support, and a lot of "4K" KVMs don't have it.

Also, 1080p divides evenly into 4K, so turn on integer scaling in the Nvidia or AMD settings and 1080p will look sharp instead of blurry.

I do use integer scaling. That's what makes 1080p bearable on my 4K display, and not other resolutions that don't divide evenly into 4K.

An annoying quirk is that I have to use the Nvidia control panel specifically to get Windows to send a 1080p signal as otherwise, it will just upscale 1080p to a 4K signal. It makes no fucking sense to me why that would be the default but whatever.

Can't you do the same thing in Windows' own Advanced Display Settings, by toggling the resolution in list of modes? (I might be remembering the naming wrong). That seems to work to change the "Active Signal Resolution" or whatever it is. But perhaps the Nvidia method is faster.

I agree that it's insane it works this way though.

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