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Comment by xxpor | Hacker News Reader

I'm 90% sure it was, but it looks like they did a major UI update to the site so it's not triggering the "that was it!" lightbulb in my brain.

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I use one, so I can confirm they work extremely well, subject to some caveats:

* The total cable length is important, both between the host / KVM and the KVM / monitor, as well as any daisy chained displays you have. I had to use certified cables to get everything working reliably with my setup.

* There's a weird interaction with BIOS power on. The boot display drivers I have freak out if they aren't the active display and fail. I solve this by switching the KVM before I turn the computer on. After everything is booted into an OS, it works fine to switch.

* Power supply quality is important. I had some issues before I made sure the power supply was reliable.

KVM switches are just inherently difficult little devices. I haven't had issues since I got it working though.

>There's a weird interaction with BIOS power on. The boot display drivers I have freak out if they aren't the active display and fail. I solve this by switching the KVM before I turn the computer on. After everything is booted into an OS, it works fine to switch.

Do you have an AMD GPU by any chance? I have the level1tech 2-head DP 1.4 KVM, with an AMD RX 560 on a Linux host, and after updating to kernel 6.4 recently my computer now boots fine without a monitor attached.

I had a similar issue where a display had to be _on_ and _connected_ (i.e: active on the KVM) at boot time, or the GPU wouldn't work at all. I could get in via SSH, so I tried various amdgpu recovery options, poking the device to reset it, reloading the kernel modules, etc., and never had any luck. I just lived with the quirk. It was problematic because if you left home with the KVM selected on the Windows guest, and needed to reboot the Linux host remotely, you'd come home to a non-functional Linux desktop.

I have a similar issue with a Nvidia 1080Ti on my old desktop. It's related to the UEFI deciding if the iGPU or the Nvidia GPU should be primary and to disable the iGPU or if the iGPU should stay enabled.

Curious how you went about determining that was the source of the issue.

I'd swap the cables around and could see video from the iGPU output.

If this is the problem, you can usually force the GPU choice one way or another in BIOS.

Nvidia on both, one consumer and one workstation. Neither CPU has built-in graphics iirc, nor do the motherboards expose the ports.

Alternatively, you may have been thinking about ConnectPro. I ordered a kvm from them around the same timeframe and it was delayed quite a bit from backorder. (Though, they also did a major UI change, so might not be able to tell either).

Two thumbs down for connect pro. I ordered their top of the line 4 computer, 2 monitor DisplayPort KVM and it took months to arrive. I could not cycle between inputs using the buttons. They were more like a suggestion to use that signal path; I would constantly need to power cycle the kvm, monitors, or both.

I ended up ditching it on eBay at a significant loss for a $30 usb switch and just switch monitor inputs manually. Far cheaper solution and way less fussy.

I had the same issue with this device. I ended up writing some code that you could run on a machine to operate the switching via the RS232 port: https://github.com/timgws/kvm-switch/

Bonus for adding 'glide and switch' functionality, so you can move the mouse to the edge of the screen and it would jump the input to the next display in your layout. It's like a hardware version of Synergy.

Very finicky device, but if you don't touch it - and you don't use any of the shortcuts - it works.

Neat! I used to use ShareMouse (pay-ware, if you want more than two machines tied together) for this, because setting it up and keeping it working are so easy compared to whatever version of Synergy existed at the time.

Synergy made me manually configure my monitors by dragging little boxes around in a window, would frequently refuse to connect, would spontaneously disconnect, and repeatedly mangled my config such that I had to keep manually configuring it over again.

With ShareMouse, it was "open a copy of it on each machine, slide mouse in direction of next machine, then optionally enable encryption (to prevent other users' instances of ShareMouse from being able to attach)".

I should also add that their customer support was totally worthless. They promised me a firmware update, and stopped responding after I confirmed my firmware version - the process to get that value was already quite arcane, so ultimately I felt like they never really had any intention of helping and were simply stalling me out.

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