Troubleshooting methods and analysis of Fan faults

A classmate's computer experiences a fault. The phenomenon is: when the fan is started, it will stop after it is turned around, and the computer will not be able to start. Sometimes, although it can be started, it will suddenly shut down after a long period of time. Exclusion steps:
1. Unplug all power plug such as the access hard drive and optical drive. Boot, power supply works properly.
2. Connect to the hard disk and the system will be able to enter, but it will be shut down in a short time. Eliminate the cause of motherboard failure.
3. Start the instance again, enter the bios, and run it. After a while, it will still shut down. Eliminate the cause of the virus.
4. Now I am sure there is a problem with the power supply. I found a power source and started it on. No problem. The system runs normally.
5. troubleshooting.
Analysis: power supply is the entry point for computers to provide power. If a problem occurs, the whole computer will have to go on strike. Otherwise, other devices may be burned out. The power supply is not completely damaged. It is possible that some of the capacitor in the power supply is damaged, resulting in reduced power and failure to provide power to the computer. So there is a 1 phenomenon, and it can work when there is no load, when there is a load, it will suddenly shut down.
Tip: Pay attention to the brand and output power when purchasing the power supply. Recommended: Great Wall, hangjia and other brands of power supply.