No Display with TB Dock 120W G4 on Elitebook X G1a

[wk-mana]

TL;DR: The HP Thunderbolt 120W G4 Dock will not display anything when restarting or cold-booting on my almost new EliteBook X G1a.  All systems mentioned below were fully-updated using Support Assistant 9.  How to fix this behavior?

For about one month, I have been using my laptop (B7HY6UT#ABA) relatively glitch-free when connecting to a USB-C Dock G5 (5TW10AA#ABA).

I had bought 2 brand new Thunderbolt 120W G4 docks (4J0A2AA#ABA) and I switched over all the connections and displays from the UBC-C G5 dock while the laptop remained on.  When I plugged the TB dock into  the laptop, every display and peripheral came up exactly the same as on the USB-C dock, so I figured everything was good.

However, when I restarted the laptop, no display came up (and I gave it plenty of time).  I tried:

1. Replugging the dock.

2. Opening the laptop and un/replugging the dock.  There was no display on the laptop or the monitors.

I did a hard shutdown by holding down the power button on the dock, then unplugged it from the laptop and powered it on and went into Windows 11 as usual.  Then:

3. I reconnected the TB dock.  Everything came up.

4. I ran HP Support Assistant v9 and sure enough, there was a firmware update available for the dock.  I ran the update, but it took a good 20 minutes to finish installing.

5. I made sure there were no pending updates in Support Assistant of any sort.

6. I restarted the laptop.  The same thing happened.  No displays.

7. I hard shut the laptop and did a cold reboot.  Same result.

8. I had 2 units of the TB dock, so I transferred everything to unit #2 and repeated the above steps.  Same results.

Here are the results of the TB dock with these other laptops that I have:

1. Elitebook 640 G9: Powered on from the dock, HP SureStart splash screen came up on all external displays, but never progressed beyond that (I waited 10 minutes).  Same result, whether the lone USB-C port was in TB mode or not.

2. Elitebook 640 G5: Powered on from the dock, booted into Windows 11.  Only 1-out-of-3 displays came up.  Windows could not detect the external keyboard or mouse. Reboot worked as well.

3. Probook 440 G11: Powered on from the dock, booted into Windows 11.  Everything worked right off the bat.  Reboot worked as well.  Same result on both USB-C ports (non-TB).

4. Elitebook 840 G8:  Powered on from the dock and rebooted just fine on 1/2 TB4 ports.  On the other one the laptop fan just ran at full throttle and nothing appeared on the external monitors.

[wk-mana · Accepted solution]

Ok, I actually found out something.

My EB X G1a had a POST boot password set.  Even though I could not see anything on the screen, if I pressed Enter, followed by my boot password, followed by Enter again, Windows would start loading *as if* the displays were working all along.

So it's the boot/splash screens that are not showing up.

The same thing happened when I rebooted.

My EB 640 G9 also had a POST password set, but even after I removed it, it stayed stuck on the HP Wolf Security splash screen.  So still not sure what's going on there.

Also, I really want to lay into the TB dock (and is the reason that I will still be returning them both) is that the same display configuration that the USB-C G5 dock was able to give me 60-60-60 Hz across all displays, the TB4 dock would only give me 60-60-30 (that last display is 4k).  TB is supposed to have MORE bandwidth than USB-C (or at least equal, if you include USB4.)  And yes, as stated in the beginning, all my drivers were up-to-date.  Anyway, so much for extracting maximum performance from the TWO TB4 ports on my EB X G1a.

[wk-mana]

One more observation:

When connecting to external displays with a dock (especially a Thunderbolt dock on a TB port), one of the external displays would flicker or flash on/off.  I resolved this on one dock by setting the internal display refresh rate of the laptop to 60 Hz (instead of the default 120 Hz).

[truohoma]

About the refresh rates, I think G4 firmware still has bugs in how it recognizes display rates. When connecting a Mac, it sees first output as 121.7 kHz / 100 Hz which doesn't make any sense. The second output works on Dell but don't know what the rates there are. There should be handshaking after Mac cover is closed but it doesn't seem to happen. This docking device has surprisingly poor quality for its price.