How to Test a Power Supply

A power supply is the main source of electricity for a computer. It runs the motherboard, processor and all the key components, such as hard and CD/DVD drives. If your power supply does not work, your computer cannot run. Usually towers or computer cases come with a power supply. However, you can purchase a power supply without any other components. Certain power supplies are specific for a motherboard. For example, a board might require a power connector for the processor to function. Check your motherboard manual before you install or test a power supply.

Difficulty: Moderate

Instructions

Things You'll Need:

• Phillips screwdriver
• Functional computer

1. Take the tower panel off. Disconnect the cables. Then unscrew the right panel. On a case, press the tabs on each side. Slide off.

2. Unhook the current power supply from the motherboard. If you have another installed, you do not have to take it out. Detach the white, heavy connector on the case. There is a tab on the side, push in to pull off. The connection is tight, so you may need to rock it back and fourth. Disconnect all of the white power connectors from the hard drive, floppy and CD/DVD drive.

3. Plug in the main white connector of the test power supply. This inserts directly into the motherboard, next to the processor fan. It is approximately 1 1/2-inch long. Align the connectors then attach by pushing the power supply tab in. It will click into place. Plug the black power cord into the outlet of the power supply and into a surge protector. Flip the switch on the power supply, to the circle position if applicable.

4. Push the "On" or "Power" button in the front of the tower. If the power supply is receiving any electricity, the fan on the supply will turn on. Before continuing, press the computer "Off" button.

5. Hook up the main devices. This will test the power connectors. Your power supply may be functioning, but a connector is out. Push the white connection tabs in to each device. Your processor may also require power. If you have a connection tab next to your CPU, insert the "J4" tab from the power supply. Push the "On" button.

6. Check each white connection on the power supply. If your computer boots normally from Step 5, turn it off again. Repeat Step 5 for every connection tab on the power supply.

Tips & Warnings

• Replace your power supply if the fan does not come on or runs slowly. In addition, if your computer does not turn on initially, more than likely a new power supply is required. If one connection tab to your devices, does not work. The power supply is still functional. There are approximately six white connectors on a supply. The power supply has only one "J4" and floppy tab. If these do not work, you may need to replace the power supply.
• Never remove the connection tabs with the power on.