How to install a computer power supply

To install a power supply in your computer, follow the steps and guidelines below-

Before getting started

Write down important information from the top or bottom of the power supply, such as the Model Number, Serial Number and specifications (e.g., voltage and watts).

Ensure you are familiar with ESD and its potential dangers.

When installing a power supply, turn the computer off and disconnect the cord connected to the power supply.

Remove previous power supply

If you are replacing a power supply inside the computer, it needs to be removed. First, disconnect the power supply from all the devices it is powering inside the computer, including the motherboard and any internal drives. Next, locate all screws that fasten the power supply to the case and remove them. Then, slide the power supply out and remove it from the computer.

Install power supply

Once the previous power supply is removed, place the new power supply into the computer and fasten the screws into the back of the power supply. Some computer cases also have a screw inside the computer case. If present, also fasten a screw into this hole.

Once the power supply is installed into the computer case and screws fastened, attach the power supply cable from the power supply to the motherboard. Next, connect each of the power connectors for the hard drive, CD drive, floppy drive, and any other peripherals.

What if I can't see the power supply sticker?

All power supplies are required by UL (formerly known as Underwriters Laboratories) to include a sticker with power ratings on it. If you're unable to locate a sticker on your power supply, the identification may be on the side that is not visible. If this is the case, you need to remove the power supply before being able to identify it. The steps in doing so are listed in the additional information links listed in the next section of this page.

After removing the power supply, if you are still unable to find a sticker with the power ratings, we recommend purchasing a new power supply. A power supply without a sticker on it is dangerous to use. It could be a very low quality unit and cause damage to your computer.

What if my power supply is already installed?

If you have a computer that is already assembled, you can determine how big the power supply is by opening the computer case and examining the unit. This Chieftec power supply is rated at 500 Watts. Many power supply manufacturers also use the wattage of the power supply in the model number. For example, this power supply's model number is APS-500S, which indicates 500W of total output.