Power supply shuts down intermittently.

Cause

Solution

 

 

If equipped with a voltage selector, voltage selector switch on

Select the proper AC voltage using the selector switch.

rear of computer chassis (some models) not switched to correct

 

line voltage (115V or 230V).

 

 

 

Power supply will not turn on because of internal power supply

Replace the power supply.

fault.

 

 

 

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

Solution

 

 

 

Processor thermal protection activated:

1.

Ensure that the computer air vents are not blocked and the

A fan may be blocked or not turning.

 

processor cooling fan is running.

 

 

OR

2.

Open the access panel, press the power button, and see if

 

the processor fan (or other system fan) spins. If the fan does

 

 

The heat sink is not properly attached to the processor.

 

not spin, make sure the fan cable is plugged onto the

 

system board header.

 

 

 

3.

If fan a plugged in and not spinning, replace it.

 

 

 

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

Solution

 

 

 

Power failure (power supply is overloaded).

1.

If equipped with a voltage selector, check that the voltage

 

 

selector, located on the rear of the power supply (some

 

 

models), is set to the appropriate voltage. Proper voltage

 

 

setting depends on your region.

 

2.

Open the access panel and ensure the 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 drives or optical drives and

 

 

expansion cards). Power on the system. If the system enters

 

 

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 devices are functioning properly.

 

4.

Replace the power supply.

 

5.

Replace the system board.

 

 

 

174 Chapter 8 Troubleshooting without diagnostics