External monitors often going off and on

[fc89]

As a previous poster who had this issue consistently for quite some time, with some recent changes to my machine the flickering issue has seemed to go away almost entirely (maybe a flicker here and there with intense graphics use like 4k multiple monitors with video or 3D modeling).

My setup is:
HP ZBook Fury 16 G9 Mobile Workstation
2x monitors (32" 4k monitors (Dell S3221QS 32 Inch Curved 4K UHD) (laptop lid closed), connected via Display Port cables
280W Thunderbolt G4 Dock.

Most notable changes have been:
Laptop reimaged and OS upgraded from Windows 10 to Windows 11 Enterprise 22H2
All BIOS, drivers, and firmware for PC and dock latest versions.

Monitor cable quality matters and anyone with this issue should go ahead and upgrade their cables to rule that out. However, I upgraded mine but for me it did not resolve my flickering issues until these changes happened. 

[bainster]

I have a G5 dock with latest firmware connected to three DVI-D monitors via adapters. This setup works perfectly with a HP Pavilion Aero 13 laptop, and with a Razer Blade 15 laptop, but fails immediately on a Lenovo Legion 7 (model 16ACHG6) with constant screen blanking every few seconds. Clearly this is not about cable quality in this case, as the dock works with 2 other laptops with exactly the same cables and monitors. There is something different about the dock's interaction with the Lenovo laptop (perhaps related to its dedicated Nvidia graphics card?).  Additionally, all three laptops work fine with a Dell WD19 dock, using exactly the same cables and monitors, so it seems that the HP G5 dock is at fault here.

[bainster]

After investigation, I believe that this problem is most likely caused by a bug or incompatibility with the Nvidia driver that results in the usable bandwidth between the laptop and dock being downgraded to DisplayPort 1.2 limits (the open source Nouveau driver on Linux works fine with exactly the same laptop, cables and dock, and so do my laptops with Intel GPU and AMD GPU, so it is likely that this is specifically a software issue with the Nvidia driver). When the DP 1.2 bandwidth limit is exceeded, either one monitor will always be black, or if the used bandwidth is close to the limit then the monitor might turn on but then blank off and on when the limit is exceeded.

For those using passive adaptors (e.g  DisplayPort to DVI or HDMI), one solution is to use active DisplayPort cables (e.g. StarTech DP2DVIS) - perhaps this is why there are reports that "better quality" cables solve the issue - the cables are not necessarily better, but do implement active conversion of the DisplayPort signal, which enables the dock to use DisplayPort 1.4 DSC (the G5 dock can only decompress DSC for an output if the output is a proper active DisplayPort SST stream). I have tested this solution and it works in my case.

Another possible solution is to plug a DisplayPort 1.4 hub (e.g. Cable Matters triple mini DisplayPort hub, which comes with a mini DP to full size adapter) into one of the DisplayPort outputs of the G5 dock. All three monitors can be plugged into the MST hub and should work (assuming the combined set up is compatible with DP1.4 DSC). I've also tested this solution and it also works in my case.

Another possible solution for people using HP laptops is to enable the "high resolution mode" DisplayPort dock  setting in the BIOS (if the setting is present). This doubles the bandwidth that the dock can use for DisplayPort, but the disadvantage is that the dock will downgrade all the dock USB ports to USB 2 speeds.

Final possible solution is to just use a different dock, e.g. the Dell WD19 does not have this problem.

[Jax38]

Hi there, note this issue was resolved for a few of us several months ago. I've reposted my solution several times. good luck. Dell doesn't work btw. That's where I started in the first place before buying the HP.

[HybridNistico]

Hey Jax38, long time no see. I wonder if you list the page in the thread where the cable fix is located so that we can all start re-directing people there… dunno, lol.

[MDD_CPI]

Thanks for all the great information, but I would like to report that the cable "fix" did not work for me.  Well, it did for about a week.  I just plug one monitor into my computer and one into the docking station, and I have not had the problem for over a month.  I hope this helps because there is nothing more frustrating then being in a video conference with clients and monitors go out.

Regardless of the cause, HP should be ashamed.  It is 2025.  Monitor issues should be well behind us.

[Grrrrrene]

"Regardless of the cause, HP should be ashamed. It is 2025. Monitor issues should be well behind us."

Maybe I am too cynical, but I don't feel like HP cares at all about this issue, or they would have replied and fixed this already. They have our money... Again, this may be overly cynical, but it's been such a long time and nothing...

[Jax38]

Agreed. It's shameful that this community had to solve it!

[bainster]

> Dell doesn't work btw.

YMMV. I've tested a Dell WD19 dock and, for me, it works with exactly the same laptop, cables and monitors that the G5 dock fails on. The WD19 (and WD19S etc.)  also have the advantage of being USB3 gen 2 (10 gbit) whereas the HP G5 is only USB3 gen 1 (5 gbit).