HP EliteBook 845 G8 constantly on and off when connected to LG Untrafile 5K display via type C

[Jeffrey8888]

Product: HP EliteBook 845 G8 Notebook PC IDS Base Model
This issue lasts for several years.

HP EliteBook 845 G8

LG Ultrafine 5K Display

https://www.lg.com/us/monitors/lg-27md5kl-b-5k-uhd-led-monitor

The display provides 94watt power charger to laptop through type-C cable, which is also used as video input.

The display keeps on and off when connected to the laptop.

When the display is on, the content is normal on the display.

There is no issue when a standalone power charger is connected to the laptop.

Same issue with HP EliteBook 840 G7.

There is no issue with Dell or Apple brand laptops.

I tried to open a case to HP support, the support guy request me to ship my display out of my country, and can't provide estimated days for issue investigation, which is unacceptable.

I am IT guy, I can do anything remotely to solve the issue.

Update: 2024-Dec-15

For HP Elite 845 G8, in windows 11, disable 'Allow the computer to turn off this device to save power' stops repeating disconnecting issue.

Device Manager > Universal Serial Bus controllers > USB Root Hub(USB 3.0) > Power Management

repeat for each usb hub device.

For HP Elite 840 G7, above setting has no difference, after installing thunderbolt drivers and HP power management software, disable several power and charge related settings in BIOS, issue disappeared.

Below link provides the hints for the solution, wish HP R&D could investigate the issue and provide a formal solution.

https://answers.microsoft.com/en-us/surface/forum/all/can-you-help-me-to-connect-my-laptop-to-my-lg-...

"This usually happens if the monitor is drawing power also from the Surface and the Surface is unable to provide enough power and so connecting the Surface to its power supply mitigates the issue. "

Most likely HP laptop turn off LG 5K monitor as it wrongly made power negotiation, actually LG 5K monitor output power to laptop instead of draw power from it.