Fixing Power Supply Problem

System without power is totally dead.

Here are problems and troubleshooting for power supply unit.



Problem 1:
Power supply shuts down intermittently.

Cause:

1. Voltage selector switch on rear of computer chassis (some models) not switched to correct line voltage (115V or 230V)
2. Power supply will not turn on because of internal power supply fault.

Solution:

1. Select the proper AC voltage using the selector switch.
2. Contact an authorized service provider to replace the power supply.

Problem 2:
Computer powered off automatically and the Power LED flashes Red two times, once every second, followed by a two second pause, and the computer beeps two times. (Beeps stop after fifth iteration but LEDs continue flashing.)

Cause:
Processor thermal protection activated: A fan may be blocked or not turning OR The heatsink is not properly attached to the processor.

Solution:

1. Ensure that the computer air vents are not blocked and the processor cooling fan is running.
2. Open hood, press power button, and see if the processor fan spins, If the processor fan is not spinning, make sure the fan's cable is plugged onto the system board header. Ensure the fan is fully/properly seated or installed.
3. If fan plugged in and seated properly, but is not spinning the replace the processor fan.
4. Reseat processor heatsink and verifythat the fan assembly is properly attached.
5. Contact an authorized reseller or service provider

Problem 3:
Power LED flashes Red four times, once every second, followed by a two second pause, and the computer beeps four times. (Beeps stop after fifth iteration but LEDs continue flashing.)

Cause:
Power failure (power supply is overloaded)

Solution:

1. Check that the voltage selector, located on the rear of the power supply (some models), is the to the appropriate voltage. Proper voltage setting depends on your region.
2. Open the hood and ensure the 4 or 6-wire power supply cable is seated into the connector on the system board.
3. Check if a device is causing the problem by removing ALL attached devices (such as hard, diskette, or optical drives, and expansion cards). Power on the system. If the system enters the POST, then power off and replace one device at a time and repeat this procedure until failure occurs. Replace the device that is causing the failure. Continue adding devices one at a time to ensure all device are functioning properly.
4. Contact an authorized service provider to replace the power supply.
5. Replace the system board.

Resources:
Windows XP Driver