Screen flicker from wall HDMI port for projector, works fine on direct

I have Acer Nitro 5 AN515-52 laptop. It has Core i7 8th Gen 8750H Processor. 16GB RAM/1TB HDD/Windows 10/NVIDIA GeForce GTX Graphics 1050 Ti 4 GB GDDR5, Samsung SSD 970 EVO Plus NVMe M.2 250GB as the main C partition.I am running Windows 10 - 64 bit, version 1903. It is up to date, all my intel drivers and Nvidia drivers are up to date. At my workplace, if I connect my laptop to the wall mounted HDMI port for the projector, the screen continuously flickers at an interval of 2 seconds, like on for 2 seconds then off for 2 seconds. This happens if I duplicate my display. If I choose extend, the problem goes away, and also when I choose 'second screen only'. My workplace has 4 halls each with one projector mounted from the ceiling. Every hall has wall HDMI port too. This wall port is connected to a conduit inside the wall that goes all the way up to the ceiling, then comes back to the projector.

However, if I connect the HDMI cable directly to the projector, screen duplicate works fine. All types of projection modes work fine this way. I have tried this with multiple HDMI cables in all the halls, but the situation remains exactly the same. The wall HDMI port works fine for others' laptops at workplace which are quite an old model of HP with a 4th or 5th generation i3 processor without any graphic card, i.e. they use intel onboard graphics.This issue has remained since day 1 of this laptop. I have DELL 22.5 inch LED monitor at home which I often connect to my laptop. Here, all the screen duplication modes work absolutely fine, be it 'duplicate', 'extend' or 'second screen only'. I have also connected my laptop to my 32 inch LED TV via an HDMI cable. There as well, all the screen duplication modes work totally fine. What seems to be the issue? And how to solve it?

The HDMI cabling in the wall is not adequate. This is more important with longer lengths of HDMI cable at higher resolutions.

The obvious thing to try is lower resolutions with your Laptop, if that works OK, then it is a wall cabling quality problem.

Others maybe using lower resolutions with older Laptops which maybe why they are OK.

Helmut said:

The HDMI cabling in the wall is not adequate. This is more important with longer lengths of HDMI cable at higher resolutions.


The obvious thing to try is lower resolutions with your Laptop, if that works OK, then it is a wall cabling quality problem.

Others maybe using lower resolutions with older Laptops which maybe why they are OK.

Thanks. I will do that and reply back here. So poor quality of cabling is used inside the wall conduit?