The power supply unit (PSU) is a central component inside the computer that supplies a direct current (DC) charge to all of the hardware installed to the PC. The power supply unit plugs into the motherboard. The motherboard transmits the electrical charge to all of the integrated devices on the board. If the motherboard is not receiving power, the computer won't turn on. To troubleshoot a motherboard that has no power, confirm the PSU is plugged into the board, make sure the PSU is turned on and check all of the power connections plugged into the PC.
Instructions
1. Shut down the computer, disconnect the power cable and all connected devices, and remove the case cover from the PC.
2. Place the computer on a flat, clean surface, then lay the PC on its side. Don't place the computer on a bed, blanket or carpeted floor.
3. Touch the chassis to ground yourself. Shine a flashlight into the computer and make sure a 20-pin or 24-pin PSU connector is securely plugged into the motherboard. The pins vary depending on the motherboard and power supply.
4. Check the back of the computer to see if there is a power switch on the power supply unit. Don't confuse the power switch with the voltage switch, which will be labeled with a set of characters such as "110V" and "220V." If there is a power switch on the back of the PSU, confirm the switch is in the "On" position.
5. Reassemble the computer. Connect another electrical device into the power outlet to test the outlet. If the outlet works, connect a different power cord to the computer. If you're using a power strip, make sure the power strip is turned on.
6. Press the On/Off button to turn on the computer. Listen closely to the computer for the sound of the fan spinning. If the fan comes on, the motherboard is receiving power, but the motherboard or some other device in the computer is defective. If the fan and power lights do not come on, the PSU may be dead.
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