HP 727pu Daisy chain, MST not working properly

[hoho1602]

Monitor HP 727pu occasionally not sharing video signal via Daisy chain to Dell U2412M (DP1.1)

Set-up is feeding video from NTB via Thunderbolt (USB-C1) OR from PC via DP+USB-C2. Switching between them (KVM).

Using Thunderbolt from NTB (USB-C1) everything works fine (every time) and video is correctly send to both monitors (HP+Dell),

Using DP+USB from PC (RTX4070 Super) works only 33% of the time. Usually Dell falls into Failsafe 640x320. After some investigation it seems it can be solved by manual re-connecting Dell DP or by Dell power OFF-ON. But this is not what I expect from Daisy-chain enabled monitor with KVM. Theoretically Dell monitor with DP1.1 should be able to work correctly as last in the chain and on SST it always worked correctly.

I was using older version of HP firmware only few hours, but the issue never happened. While after firmware update it is difficult to connect Dell correctly in FullHD. Usually need to amke power-reset of Dell every time I disconnect NTB and witch back to PC.
Is there a possibility to return to older version of HP firmware or solve this by firmware update of HP?
I am not interested in buying MST splitter or purchasing new monitor when my current set-up should be compatible.

 

Thank you for your suggestions.

[70007]

Hello Hoho1602,

Thank you for posting your concern,

Troubleshooting Daisy Chain Video Signal Issues on HP Series 7 Pro 27 inch QHD Monitor

If you’re experiencing issues with the HP Series 7 Pro 27 inch QHD Thunderbolt 4 Monitor occasionally not sharing video signals via daisy chain to a Dell U2412M, here are some steps you can follow to potentially resolve the issue:

1. Verify Cable Connections and Quality:

   • Ensure all cables are securely connected.
   • Verify that the cables used are of high quality and compatible with your monitor and video output configuration. Sometimes, low-quality cables might not support stable video signals, especially in high-resolution setups.

2. Update Graphics Drivers:

   • Ensure that the PC's graphics drivers, especially for the RTX 4070 Super, are up to date. Visit the NVIDIA website to download the latest drivers and install them.

3. Check Monitor Firmware:

   • Ensure that your HP monitor's firmware is updated to the latest version available. You can check for firmware updates on the HP Support website.

4. Optimize Monitor Settings:

   • Access the monitor's on-screen display (OSD) menu and ensure the DisplayPort (DP) version is set correctly. Since the Dell monitor uses DP1.1, ensure that the input select settings of the HP monitor support DP1.1 compatibility.
   • Also, check if the monitor is set for daisy chain (DP MST) capability and that it is enabled.

5. Test Different Configuration:

   • Test a different configuration order in your daisy chain setup to see if there is any change in the behavior.
   • Consider using direct connections for testing purposes to see if the issue persists when directly connecting each monitor individually to the PC.

6. Change Video Output Settings:

   • On your PC, adjust the video output settings. Lowering the output resolution and refresh rate from the RTX 4070 could stabilize the connection with a DP 1.1 monitor like the Dell U2412M.

7. Review KVM and USB Settings:

   • If switching inputs with the KVM is causing inconsistencies, review the USB settings within the monitor’s OSD to ensure USB-C configurations are optimized for KVM functions.

8. Monitor Testing:

   • Run a monitor self-test feature, if available, to ensure the monitors themselves are functioning as expected without external devices connected.

If the problem persists, consider reaching out to HP support or Dell support for further guidance based on their monitor’s interaction behaviors and potential compatibility advisories. Additionally, compatibility or limitations with certain features (such as daisy chaining with DP1.1) should be checked and ruled out.