Symptoms of a Bad Power Supply

Nothing seems more frustrating than a failing computer. They pick the most inconvenient times to misbehave—the presentation with the CEO, a customer demonstration and even Bill Gates' presentation of Windows 98. The causes and symptoms of faulty power supplies overlap with other problems such as virus and spyware infections, defective hardware, recent hardware upgrades or simply an overloaded power supply. Furthermore, computer power supplies can be damaged by recent thunderstorms, power surges and brownouts.

A computer power supply out of the case


Components inside a power supply

If you experience electrical shock, hear noises, smell anything burning or see sparks, always unplug the computer at the outlet. This point cannot be stressed enough. Leaving the computer running with a faulty power supply can result in equipment damage, loss of data, fire and death.

Erratic Operation

If your computer randomly reboots or locks up during normal operation or power-up, the power supply may be overloaded or malfunctioning. Random memory or hardware errors also can happen. Keep in mind that erratic operation can also have other causes such as defective hardware, inefficiently written software or malware including viruses and spyware.

Flickering Lights

If the computer's system lights or LEDs flicker or appear to be dim, or if there are no lights on, the power supply may be bad or overloaded.

Unusual Noises or Silence

Fans are common causes of power supply failure.

If you hear any unusual noises coming from inside the computer case, turn it off immediately and unplug it regardless of what programs may be running. Unusual noises include sparking sounds or a malfunctioning fan. Just as concerning is not hearing anything when you power up your computer. If you don't hear the fan or disks rotating, or if the system is completely dead, the power supply may be the culprit.

Smoking or Sparking

Any time you see sparks, smell something burning or see smoke, turn off and unplug the computer immediately to mitigate further damage and to prevent a fire. Smoking is just as bad for computers as it is for humans, only more immediate.

Electric Shock

If you receive electric shocks when you touch the computer case, turn off and unplug the computer. Take the computer to a repair shop for service.

Computer Trips the Circuit Breaker

Always know where your circuit breakers are.

If the computer trips a breaker or blows fuses when turned on, or if there is severe sparking at the electrical outlet or outlet strip, unplug everything at the wall outlet. Besides short circuits in the computer, miswired outlets can cause power problems and shock risks.


The wires and sockets of a power supply

To assure power is getting to the equipment, check that all power cords and wires are connected and secured in their sockets. Also, check that all switches are in their appropriate positions—on outlet strips, at the circuit breaker and on the computer.

If recent hardware has been added, disconnect it to see if the computer functions as before—more hardware devices may overload the power supply.


Capacitors on a circuit board

Power supplies have capacitors that store lethal voltages. Never open a power supply or stick anything into its openings. If you are inexperienced in maintaining computers, take your computer to a repair shop where a technician can assess what needs to be done. Always unplug the computer before disassembling the its case. If you suspect damage to the building circuitry, call a qualified electrician to assess the situation.