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January 30th, 2025 09:16

P2423DE, daisy chain with display port 1.2

Hi,

I recently bought two Dell P2423DE monitors for work which I want to connect to my Lenovo X1 Carbon Gen6 laptop.
My setup is: Laptop -> USB-C -> Montitor1 -> DP-out to DP-in -> Monitor2.
This only gives picture on laptop and monitor1.

I also have an Dell P2421DC (older version of P2423DE) and using P2421DC as monitor1 the setup works like below:
Laptop -> USB-C -> P2421DC -> DP-out to DP-in -> P2423DE.

I see here: https://www.dell.com/support/kbdoc/en-us/000200307/dell-p2423de-monitor-usage-and-troubleshooting-guide that the default factory setting for P2423DE is display port version 1.4. My laptop only has 1.2 and I guess this is the reason why my first setup (Laptop -> P2423DE -> P2432DE) does not work out of the box?

But the troubleshooting guide also tells that one can change the monitor to display port version 1.2. 
When I do the mentioned steps:

  1. Press the joystick (Figure 6) on the monitor to enter the On-Screen Display (OSD) Menu.
  2. Press up or down to highlight Input Source in the menu and press on the joystick to select.
  3. Press up or down to highlight DP in the menu.
  4. Press and hold on the joystick for approximately 10 s until the DisplayPort configuration message appears.

I never got the "DisplayPort configuration" message. I only get "No DP cable" (which is true since I'm connected via USB-C). So does the steps above only work I'm connected via a DP-cable from my laptop or should it work in my case also? 

My firmware version is M2C106.

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January 30th, 2025 09:27

I forgot to mention that I have MST enabled on both monitors.

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January 30th, 2025 16:41

Dell Support must verify the ownership and warranty status. Click the blue "Get Help Now" on the right to start a private live chat session. Share the private P2423DE Service Tags with them.

the steps above only work I'm connected via a DP-cable from my laptop
* Correct. Those steps assume the PC source is DP out port.

MST On should only be on the first primary monitor. The second daisy chained monitor should be MST Off.

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January 31st, 2025 07:29

@DELL-Chris M​ 

Thanks for your reply.

I will try that later today but I'm pretty sure I did not turn it off when I did:
Laptop -> P2421DC -> P2423DE.

But based on your answer I assume that my setup Laptop -> P2423DE -> P2423DE should work? 

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January 31st, 2025 12:59

What year release is your Lenovo X1 Carbon Gen6?
Is the Lenovo AC power adapter connected to the Laptop when trying two monitor daisy chain?

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January 31st, 2025 15:10

@DELL-Chris M​ 

It was released in 2018. X1 Carbon (6th Gen) 20KH is the model number.

No, no power adapter is connected. The only cable attached to the computer is the USB-C cable that was included with the P2423DE monitor. (And the same cable that was used when I successfully tried Laptop > P2421DC -> P2423DE).

Community Manager

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56.8K Posts

January 31st, 2025 15:15

For troubleshooting purposes, connect the provided Lenovo AC power adapter to the Lenovo X1 Carbon Gen6, then retest.

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February 2nd, 2025 13:16

No difference when the provided Lenovo AC power adapter is connected.

I also tried to setting the second monitor to MST=off and the only difference was that I now got picture on monitor2 instead of monitor 1.

I guess this boils down to the display port version 1.4? I tried the four steps to change the display port version on monitor 2 (when I in fact had DP-signal via DP-out on monitor 1) but the menu did not show up this time either.

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February 2nd, 2025 16:08

I actually got it to work now.

If I set the USB-C Prioritization to "High resolution" on monitor 1 it works even if I have "MST On" even on the second monitor. I guess the downside of this is that I'm limited to only USB 2.0 speeds in the USB-hub. I'm currently connected with an ethernet cable via the monitors ethernet port so will see if notice any impacts of throughput and latency.

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