HP DisplayPort Port Flex IO, no function, MST not worki

[msssm]

Hi,

I upgraded the ProDesk 600 G5 with a HP DisplayPort Port Flex IO, getting a 3rd DisplayPort.

On Linux it doesn't provide any signal, no display gets detected. I did not find any setting in the setup/BIOS to enable it. Previously a VGA flex port was installed.

The installation seemed easy, the flex card was fitting and the screws were also fitting exactly. I hope the contact to the mainboard is working. Do I need to enable something?

Having a i7-9700, is that Intel graphic capable to drive 3 screens of QHD (2560x1440) actually?

Then I tried Daisy chain (MST), plugging one screen into the other. I have no experience with MST yet. I got a copy clone of the 1st screen on the 2nd, the computer didn't see the 2nd screen. But I don't need a copy, but a separate screen. Then I found in the screen setup to enable MST. After that all screens are black. I need to disconnect all screens to be able to get to the screen setup again to disable MST.

Is the Intel graphic of this machine capable to do MST? In the Quickspecs I only find:

QuickSpecs HP ProDesk 600 G5 Business Desktops PC
Technical Specifications – Graphics
Not all configuration components are available in all regions/countries.
c06336904 – DA-16477 – Worldwide — Version 18 — September 16, 2020
Page 40
GRAPHICS
Intel® UHD Graphics (integrated)
Graphics Controller Integrated
DisplayPort™
Multimode capable; supports HDCP, Display Port Audio (2 streams), HBR2 link rates and Multi-
Stream Technology for a maximum of 3 displays connected to any output controlled by Intel®
Graphics
HDMI
Supports HDMI 2.0a features
Supports HDCP 2.2
Supports audio over HDMI

Quickspecs of the Flex IO card: https://h20195.www2.hp.com/v2/GetDocument.aspx?docname=c06042607

Quickspecs of the ProDesk 600 G5: https://www.dokmeha.com/wp-content/uploads/2021/02/QuickSpecs-HP-ProDesk-600-G5-Business-Desktops-PC...

[Jupitero · Accepted solution]

Hi.

Did you get the DP to work? If not, try reseating the DP board again. Press the board, at the point of the connector, firmly into place and only then screw it in. There is nothing to enable once the board is in place, the DP output should be available automatically.

Did the VGA flex port work before you removed it? Try it again - with VGA display - to verify the system board connector functionality. If VGA works and DP doesn't, then I would assume a defect in the DP flex module.

Check the cables and try replacing them, cables can be faulty as well.

Make sure your BIOS is the latest version.

If your Linux distro is old, try one of the latest distros with kernel 6.x for improved drivers. If you can, try with Windows as well.

About MST:

Please re-read the Quickspecs page you quoted. It explicitly states:

Multi-Stream Technology for a maximum of 3 displays connected to any output controlled by Intel® Graphics

(Multi-Stream Technology = MST)

Keep in mind that there is limited bandwidth available in Displayport 1.2, and you may not be able to get optimal resolution/color depth/refresh rate in MST mode. Start with a basic FullHD resolution at 60Hz first. Check the monitor manual and OSD menus for MST/DP settings.

If you are daisy chaining monitors only the first monitor in the chain must support MST. If your monitors have multiple DP ports, only the DP output port can be used for daisy chaining.

If you still can't get this to work, include your monitor information and BIOS version in your next reply.

[msssm]

HP HP ProDesk 600 G5 SFF/8597, BIOS R07 Ver. 02.22.00 12/30/2024

Displays: Dell UltraSharp U2520D (3x)

I was not able to daisy-chain 2 screens on one of the 2 main DisplayPorts. The screen was initially cloned when I didn't have MST enabled on the screen, but after enabling MST on the intermediate screen, both screens went black.

I'm going to try re-installing the Flex IO card.

Should the 3rd display port be always shown in the operating system, showing with xrandr --listproviders ? The Intel graphic should always have 3 heads internally, not only after installing the Flex IO which actually is no graphics hardware but only a connector to the PCIe. If I can't get the Flex IO working for whatever reason, I could also add some PCIe expansion card like a Pass-Through adapter without GPU. I don't need 3d acceleration, only big screens and resolutions, and selected an Intel system with internal graphics for powersavings.

[msssm]

Right, switching back to the Flex IO VGA, working. Switching back to the Flex IO DP, working as well. Thanks!

It was just not properly mounted to the electrical contacts.

Finally I also understand, that xrandr --listproviders does not list this socket until it is installed and detected.

Very good job driving now 3xDisplayPort on the internal Intel graphics with 2560x1440 each, for office jobs only, no 3D.

[Jupitero]

Glad you got it working - and nice of you to clarify the xrandr functionality for other readers as well!

Since I do not have this computer model nor those Dell monitors, I can only refer to the HP quickspecs which explicitly claims MST support; and Dell User's Guide which has well illustrated MST cabling instructions.

Of course, this is all academic now that you have the third output working. 🙂