HP Thunderbolt Dock G2 - faulty output?

[James_SCH]

So I have the HP Thunderbolt Dock 120W G2 and 2x HP Z27 27-inch 4K UHD Displays.

I did have both monitors running just fine at 4K but not anymore.

Now only one of the displays works just fine (at 4K) but the other doesn't.

To be precise when I connect the affected monitor via DP-DP the monitor is not detected.

When I connect the affected monitor via DP-miniDP the max resolution is 1920x1080.

It seems to me that either the dock is failing or the monitor has a dodgy EDID.

Anyone else seeing this? This is notebook agnostic.

Also, just for laughs the serial number on the dock is not recognised by the HP system 😞

[soccer_dan]

due to the way bandwidth is split coming across the usb-c/tb port into the dock, in order to support 2 4k monitors, you need to connect one to a dp port and the other to the usb-c port via a usb-c/dp or hdmi adapter... the dp hub on the dock does not have the capability to support 2 independent 4k displays... too much performance required for the hub

[James_SCH]

To clarify, when I say 4K I meant 4K 30Hz which is what both of my monitors were running at until I had this issue.

I would accept your explanation if I wanted to run them at 4K 60Hz but I'm not.

I am assuming there is an MST hub in the dock covering the 2x DisplayPort outputs. It sounds like there are only 4 lanes of DisplayPort 1.2 feeding the MST hub hence a maximum of 2x 4K 30Hz being available when 2 monitors are connected to the DisplayPort outputs.

Thoughts?

[James_SCH]

For anyone else with this issue I can confirm that running the HP Thunderbolt Dock G2 v1.0.57.1 firmware installer does not help.

[James_SCH · Accepted solution]

Problem (so far) fixed.

First I restored the DP-DP affected monitor to its factory default settings via it's OSD menu.

In my case this was Main Menu > Management > Factory Reset

This got pixels to show on the display.

Then I had to enter Settings > Display and then for each monitor enter their Advanced display settings.

There I set the monitor at 4K (60Hz) to 4K 30Hz and the monitor at 1080p to 4K 30Hz