There is a problem with the connection cable between the monitor and the computer. Check the connection cable between the monitor and the computer;

2. There is a problem with the memory module. The memory module has poor contact. Take out the memory module and wipe it with alcohol. After a while, restart the computer and test;

3. The monitor is broken, you need to power on the monitor separately to confirm whether it is ok;

3. The motherboard has an electrostatic reaction, remove the components in the picture below and discharge them

5. If there is a problem with the motherboard, this is more professional. It is better to go to a professional to repair the computer.

Motherboard:

Computer chassis motherboard, also called Mainboard, system board or motherboard; it is divided into two types: commercial motherboard and industrial motherboard. It is installed in the chassis and is one of the most basic and important components of the microcomputer. The motherboard is generally a rectangular circuit board, on which are installed the main circuit systems that make up the computer. Generally, there are BIOS chips, I/O control chips, key and panel control switch interfaces, indicator light connectors, expansion slots, motherboards and plug-in cards. DC power supply connectors and other components.