Dell E6440 flashing when connected to TV via HDMI

Hello

I am facing some issues, when connecting my Dell E6440 laptop to my LG 55LB650V flat screen.

I connect the laptop to the TV via HDMI-cable and I have been trying different cables. The computer has both an Intel HD Graphics 4600 and an AMD Radeon HD 8690M graphic card.

When I connect my computer to the TV the screen starts flashing black, every 5 seconds or so. Every time I open a new program the screen flashes and it is also happening sometimes when I do not use the computer.

The computer runs at 1600x900 and the TV is a full HD. I have tried to alter the resolution to both and I also tried to use a custom scaling level of 120 % (as 1920 is 120 % of 1600). I have also changed the refresh rate to 59p HZ and 60p HZ, but that made no difference. I have found out that if using the 60i HZ the screen would not flash (at least it have not yet).

So at the moment I can use the computer on the TV, but of course I would like to know why the screen is flashing when using 59p or 60p HZ and know what I can do, so I could use these refresh rates.

I hope that someone could make me wiser on this problem and maybe give me a solution. If anyone knows, I would also be happy to know what the best custom scaling level to use when using a 1600x900 laptop on a full HD TV is.

I really appreciate any help. Thank you in advance!

I have recorded two videos that shows the problem:

Part 1: https://youtu.be/DzKU0a0qiqo

Part 2: https://youtu.be/ruddUJEkl7Q