Accessing a single computer from two desks on separate floors

January 8, 2024 4:38 PM

I'm moving into a new house soon. The basement has a finished office where my Windows workstation will be located. I have a 32-inch 4K monitor. I'd like to have the ability to connect to that computer from a bedroom located on the first floor.

I know I can just purchase a second computer and use Windows Remote Desktop or VNC to connect to the computer in the basement, but I'd rather avoid that option. Can I get a second 32-inch 4K monitor, keyboard, and mouse – and somehow connect them directly to the computer in the basement? I have a handyman who can run any necessary cables from the first floor down to the basement office.

My Google-fu suggests that this device might work, but I'm not sure. When I'm using the rig upstairs, I want the monitor downstairs to be blank (or locked), and vice-versa. Can I do that with the KVM extender?

posted by akk2014 to Computers & Internet (13 answers total)

In theory yeah, a KVM switch is the right tool. I don’t know that brand. In practice I have always found it more reliable to drag a laptop around and set up a couple different workstations, then just remote into whatever computer I need from that laptop. But we are a two-person six computer household so may be outliers.
posted by aspersioncast at 5:05 PM on January 8, 2024

Can you explain why you don't want to use Remote Desktop for this? Is it for streaming/gaming?
What GPU is in your computer?
posted by snuffleupagus at 5:05 PM on January 8, 2024

Also, HDMI (on a regular cable) is not meant to go more than around 50 feet, USB 2 is around 15 feet, USB 3 is around 10 (without any hubs or active cables/extenders).
posted by snuffleupagus at 5:19 PM on January 8, 2024 [1 favorite]

Response by poster: @snuffleupagus: I didn't want to spend the money to buy another computer. Also, I don't like the latency introduced by Windows Remote Desktop. I know it's not bad, but it's still slightly annoying. The computer is not going to be used for gaming but possibly for streaming. The GPU is an AMD Radeon RX570.

@aspersioncast: As I understand it, KVM switches are typically used to share a single monitor, keyboard, and mouse between two (or more) computers – whereas I'm trying to share a single computer between two monitors, keyboards, and mice.
posted by akk2014 at 6:38 PM on January 8, 2024

Assuming USB/HDMI/etc extension cables can reach from upstairs and still work (obv. test this before you drill) then yes, you can simply plug in a second KVM set, configure the screens to mirror each other and it'll work but the other KVM will still work too.

If you add in a KVM switch 'backwards' (i.e. 2KVM+1PC) then you can skip the mirroring and the other KVM set will be inoperable but you may have to go to wherever the KVM switch is.

If they won't reach then yes, something like that device is what you need. Though that particular one is massively overkill as it's designed to support up to 16 different KVM-PC pairs on the same network.
posted by gible at 8:30 PM on January 8, 2024

Personally, assuming I had Ethernet connectivity between the locations, I'd run Sunshine on the shared computer and use Moonlight on whatever cheap Mini-PC I could get ahold of. I can't promise that AMD's hardware video encoding is as low latency as Nvidia's, but if it is you'll see less than 5ms of latency across a GigE network.
posted by wierdo at 9:39 PM on January 8, 2024

According to the HDMI 2.1 spec FAQ a passive cable that meets the full spec will only be good for 5 meters, so you may need an extender or active cable if you're going to approach or exceed that distance.

Given that I'm currently debugging a setup that does 4k at 2m, I can say that the cables and connectors, when copy protection is active (streaming, blu-ray), are extremely fussy. Maybe not for desktop use though.
posted by zippy at 9:57 PM on January 8, 2024 [1 favorite]

You can get expensive long-distance optical HDMI cables and/or cheaper HDMI-over-Ethernet wall cabling (search 'HDMI extender') to mirror the contents of that downstairs screen onto another upstairs. You might run multiple longer cables for USB connecting keyboard/mouse/webcam/audio headset.
posted by k3ninho at 5:14 AM on January 9, 2024 [1 favorite]

If you add in a KVM switch 'backwards' (i.e. 2KVM+1PC)

I'm not aware of any KVM switch that will work that way, except those ancient ones that are just a multipole rotary switch (and those would work only for VGA and a PS/2 mouse/kbd). All other KVM switches that I know of have dedicated inputs and outputs, usually with functions like detecting a keyboard to provide hotkey switching and emulating a keyboard+mouse to any system not selected. Using one 'in reverse' just won't work even if you bodge the USB cables to fit.

What you would be looking for in this setup is a multiport switch for the video (most 'standalone' HDMI switches can be used in both directions), and an USB switch providing two pairs of inputs (or two single inputs with an upstream hub) to a single output. You would also need a HDMI extender for the upstairs screen (as you linked already). This will do the job, but the switches won't work in tandem and won't do hotkey switching.
posted by Stoneshop at 6:13 AM on January 9, 2024

HDMI Distribution over your Home Network? Low-Cost HDMI Matrix using IP-Based Hardware

TESmart HDMI KVM extender
posted by snuffleupagus at 6:25 AM on January 9, 2024

I did exactly this at my old house. Recording studio in basement, work office upstairs, and about a 75 foot cable run between them.

I had both sets of monitors just mirroring each other so I didn’t need any kind of switches.

IIRC, for audio I used an optical cable, for mouse/keyboard I used a usb to Ethernet extender, and for video I used hdmi to Ethernet extender. I used cat7 cable but that wasn’t enough to kill the AC induced noise. So I eventually just got some cheap metal electrical conduit and ran most of the cable through that. Grounding the conduit helped even more. At some point I wanted to use Bluetooth accessories so I found a directional antenna to plug in that helped with those.
posted by MonsieurBon at 6:27 AM on January 9, 2024 [6 favorites]

I love the reframe that MonsieurBon has here. Given two displays set to mirror and two sets of input devices connected at the same time, you don't really have to worry about switching as long as you don't have someone messing with the other inputs as you are using it, in my case, I'd need to switch off my other keyboard to prevent any cat typing...
posted by advicepig at 7:20 AM on January 9, 2024

advicepig: I'd need to switch off my other keyboard to prevent any cat typing...

Back in the day I had a low shelf over my desk that the monitor (big heavy CRT Sony thing) sat on. Its function was twofold: lifting the monitor a bit, and providing a nook to slide the keyboard into, to keep my cat from placing orders with wholesaletuna.com and yummyfreshsalmon.net
posted by Stoneshop at 11:42 AM on January 9, 2024 [1 favorite]