I recently bought a Dell laptop and updated it to Windows 10. A couple of days ago I realised that there is a flickering horizontal line just about the windows 10 menu icon. The line is about an inch and it flashes on certain applications. The first time I realised it was there was when I expanded Microsoft Word window to full screen. The bottom left blue taskbar started flickering. I can create the effect with some of other applications by dragging the window of those applications onto that location or touching the virtual horizontal line along the flickering point by the bottom of the application's bottom taskbar.
So far, I have tried so many different versions of graphics drivers. The screen is 4K Samsung SDC4C46 touch screen. Apart from Intel HD 5500 there is AMD Radeon R7 M270 4GB DDR3 discrete graphics card in the system. When I connect the laptop to an external monitor by HDMI cable the flickering goes away on both screens. Then I take out the HDMI cable and disable the AMD graphics, the flickering still continues. Next step, I disable both of the graphics card, the flickering goes away. And finally I enable AMD graphics while the Intel HD 5500 is disabled, again no flickering.
I have spent my last two days on this issue by trying many alternatives and testing the cards.
Could this be Windows 10 graphics card driver issue, something else?