HP Elitebook 745 G6 External 4K monitor detected but no signal

[ChristianHlsm]

Hi,

I have a problem with my HP Elitebook 745 G6 with AMD Chipset (AMD Ryzen 5 PRO 3500U w/Radeon Vega Mobile Gfx.)

I have previously been able to connect my Acer H277HK 4K(UHD) monitor as secondary monitor via the HDMI connection on the laptop. This used to work, although i always had to turn GPU scaling off and then on again for it to work.

Now it doesn't work anymore. I assume it stopped working after a Windows software update as i could not open the AMD Radeon software due to a mismatch between the real driver version and the version the AMD software thought was installed.

This issue is however fixed, and I uninstalled the graphic drivers and installed the newest version.

Now when I connect the Acer screen via HDMI the screen is detected as a monitor in both Windows settings and in the AMD software. However the screen does not detect any signal from the laptop.

It worked before with the same cable and the setup works just fine on a HP Elitebook with Intel Chipset.

I have no clue what to do in order to get it fixed.

I tried to do the following with out luck.

• Uninstalling and reinstalling the graphic card drivers incl. AMD software.
• All kinds of settings, GPU rendering ON/OFF, AMD Freesync ON/OFF, extent screen, duplicate screen, various resolutions and update frequencies.
• Connecting the screen via HP dock --> DP to HDMI adapter --> Acer monitor
• Connecting the screen via USB-C --> USB C to HDMI adapter --> Acer monitor.

As mentioned it works on a HP Elitebook 840 G6 that has Intel chipset and also on a Fujitsu laptop.

And it also used to work with the exact same hardware/cables - although not very smooth as you had to switch settings back and forth for it to work.

Does anyone have a suggestions on the problem and how to fix it?

[ChristianHlsm]

Small update - if anyone has the same issue (no real answer to the problem yet though).

I now managed to get a signal on my monitor, by doing the following:
Borrowing a HP DisplayLink 4K USB-C "Dock" and attaching the Acer H277HK monitor via HDMI.

At first it was not working. Screen was recognized both in Windows and in the AMD software as second monitor, but still no signal.

Rebooted the PC, still no signal. Changed the resolution down to a lower setting. Now I heard a noise in the build in speakers of the external monitor and the image was shown. Checked the AMD software - the secondary monitor was not recognized - although I now have signal.

Now detached the DisplayLink 4K USB-C "Dock", and connected the screen directly via HDMI. Now this also works??!.
And I was even allowed to change the resolution up to the native resolution of the monitor (3840x2160px).

It really seems like there is a software/driver bug of some kind. But unfortunately I have no good clue on how to find it.

I would still like a feedback if someone has a good idea on how to solve the issue?

[ChristianHlsm]

It seems like it is due to the refreshrate.

If I select 3840x2160px @ 60 Hz it doens't work.

If I select 3840x2160px @ 630 Hz it suddenly works.

The specs of the laptop says HDMI 2.0 and should support HDMI 2.0.

Also I have another laptop running 60 Hz on the same cable without issues.
The other laptop has Intel Chipset though.