So far it is a hardware issue 99 times out of 100. You can try a factory reset (bye bye files) but repair is unlikely due to OOW costs.
If you need a cheap, this one (link to follow) looks to be a step up in a few ways.
I have an Asus x551Mav laptop. 3 days ago a weird white horizontal line start to appear across the screen. It shows up every 3 seconds and last for 2 seconds. First day appeared the problem only was for like 5 minutes then stopped happening, 2 days later last for half and hour and today is still happening when i woke up.
Here is the example, sorry bad quality https://youtu.be/6dF2KluDxdo
I connected the laptop to my samsung 32 led tv and the line doesnt show up there, i activated the duplicates screen and still the white line appear in LAPTOP but not in tv. Question is... this the fact discard driver issues and software issues in general? Do i have to replace the screen or is it a possibility that if i clean the cables between the motherboard and the screen it will fix it? BTW i start the PC in safe mode and the problem is still there. My original laptop is broken so i had to buy another one not from ASUS, dont know if that is related since i have read about powew issues.
I have Windows 10, Intel HD graphics and 4 gb ram. My original laptop is broken so i had to buy another one not from ASUS, dont know if that is related since i have read about powe issues.