How to use All in one PC as the external monitor.

[MyNew3rdACC]

I got 

Hp proone 400 g5  4NT84EA it have (hdmi input)  and DisplayPort out 

I want use it as minitor with prodesk 450G5. Tryed DisplayPort (DisplayPort-HDMI cable) Hdmi port on prodesk.

All works with normal monitor. 

I need to see screen on the proone 400  too. Using as the main only monitor. 

IMHO:

 the proone 440 G6 have OSD  buttons on the bottom of the screen  but proone 400 g5 dont have such option.  so i cant swith input signal 

[BeemerBiker]

I do not have the HP ProOne 400 g5 but I looked at the specification and the additional (optional) board that has  HDMI seems to be only for input, not output.  Its part number is L31893-001 

Other optional boards that fit include a serial port and a display port.  There is no simple way a serial port can be configured as an output to drive a monitor so I assume they are all inputs which makes sense.

[edit]  Not sure what ai was thinking of.  All these ports are for output.  I actually had the top line correct "output not input" but changed it.

If the system has Wi-Fi you can project on it from your other system if it also has Wi-Fi

There is a detailed guide to make the laptop (or deskktop) a second or external monitor here

https://www.techadvisor.com/how-to/laptop/laptop-second-monitor-3674679/

[MyNew3rdACC]

"HP ProOne 400 g5  (optional) board that has  HDMI seems to be only for input, not output.  Its part number is L31893-001 "

This is exactly what I have and what I want to use as input - like monitor.

Wi-fi ? i dont have windows or linux its dos or bios screen. and  Prodesk and Proone not coinected to any network. 

[BeemerBiker]

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@MyNew3rdACC wrote:

"HP ProOne 400 g5  (optional) board that has  HDMI seems to be only for input, not output.  Its part number is L31893-001 "

This is exactly what I have and what I want to use as input - like monitor.

Wi-fi ? i dont have windows or linux its dos or bios screen. and  Prodesk and Proone not coinected to any network. 

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Sorry, my mistake.  as far as I can tell both of these system are similar and have ports, some optional, and those are used to allow connection to external monitors.  One option was a serial port which is bi-directional and it can simulate a dumb (serial) terminal.  You want to use one of them as an external monitor.  I do not believe that can be done.  

You are correct about the Wi-Fi as windows 10 or 11 is required to project from one system to another.

My mistake.