ReadImportant Computer Repair Safety Tipsbefore proceeding with testing a power supply unit.

Do not neglect this step.

However, it may not be suitable for those who are new to computer maintenance.

Before proceeding, be sure to read the safety tips.

when you’ve got done so, you might begin the process.

Then,bring up the case.

Unplug the power connectors from every internal equipment inside the computer.

Each group of wires should terminate at one or more power connectors.

Group all the power cables and connectors together for easy testing.

Check to confirm that thepower supply voltage switchlocated on the power supply is properly set for your country.

In the U.S., this switch should be set to 110V/115V.

Plug both theATX 24-pin Motherboard Power ConnectorandATX 4-pin Motherboard Power Connectorinto the power supply tester.

Plug the power supply into a live outlet and flip the switch on the back.

Some power supplies don’t have a switch on the back.

If the PSU you’re testing doesn’t, plugging in the equipment is sufficient to provide power.

Press and hold theON/OFFbutton on the power supply tester.

You should hear the fan inside the power supply begin to run.

Just because the fan is running doesn’t mean your power supply is supplying power to your devices properly.

Also, some power supply fans don’t run when being tested even though the PSU is fine.

you oughta continue testing to confirm anything.

Confirm the LCD on the power supply tester is lit, and you see numbers in all the fields.

CheckPower Supply Voltage Tolerancesand confirm that the voltages reported by the power supply tester are within approved limits.

If all the reported voltages fall within tolerance, you’ve confirmed that your power supply is working properly.

If you’d like to test the individualperipheralpower connectors, continue testing.

If not, skip to Step 14.

Turn off the switch on the back of the power supply and unplug it from the wall.

Don’t connect more than one of these peripheral power connectors at a time.

Plug in the power supply and then flip on the switch on the back if you have one.

If not, replace the power supply.

Only the SATA power connector delivers +3.3 VDC.

Repeat this process, beginning with Step 11, testing the voltages for the other power connectors.

Amanual power supply test using a multimeter, while not a perfect load test, comes closer.

There should be little doubt about whether your PSU is working properly after testing it with a PSU tester.

However, there are several reasons a computer won’t start other than a malfunctioning power supply.

SeeHow to Fix a Computer That Won’t Turn Onfor a troubleshooting guide and more help with this problem.