To troubleshoot a flickering screen, first update the video card drivers, and then make sure the CPU is not overheating or being overclocked. Then connect a second monitor to the unit.
# If the same flickering happens on the second monitor, then the first computer’s monitor is not the problem. In this case, replace the video card or the flex cable.
# If the second monitor is fine, then the first computer’s monitor is the problem. In this case, replace the screen.