When you see lines like these across your LCD, it indicates a problem with your monitor's electrolytic capacitors. A faulty filter capacitor in the power supply board (SMPS board) can cause horizontal lines across your monitor screen.
Horizontal screen lines are one of the most visible problems I see in LCD monitors that are 3-7 years old. It can happen as much from heat, humidity & less-than-ideal operating conditions, as it can from fluctuating current supply or manufacturing defects.
The way to repair horizontal screen lines is by removing the capacitors from the printed circuit board (PCB) and testing them with a LCR meter.
If it shows zero, there's your confirmation that the specific capacitor needs to be replaced.
