How to Replace PC Power Supply

Filetonic is the authority on file extensions, dll files and exe files, the filetonic library has over 13000 file types and counting. Click File Extensions to learn more

Changing the Power Supply is soooo Easy, Really.

Replacing the power supply in your PC is relatively easy, and doesn’t require any specialized knowledge. A few wires, knowing the type of power supply you have, and a Phillips head screwdriver is all you need.

Unplug your Computer First, Seriously

Before opening your computer’s case and taking anything out, turn off the computer and disconnect the power cable. Set the computer on a rubber or anti-static mat if possible.

Next, look at the back of the computer. On most cases (half-tower and mini-tower AXT cases) the power supply will be located at the top. Try and locate the wattage (not to be confused with the little red AC selector). More than likely it won’t be there, but it never hurts to check. If it isn’t, the next step is to take off the PC’s side panel.

This is done by taking the two to four screws out from the edge on the right. It’ll be the screws that go into the little overlapping piece. Once they’re removed, slide the panel back toward you. Pull it back and then out slowly because there could be a case fan present with wires attached to the motherboard. (The wires could also be attached to one of the interior power connectors coming off the power supply.)

Make Sure YOU are Grounded

Before touching anything on the inside of the PC, press your hands on a metal or rubber surface not attached to the computer. This is done because a static discharge from your body could damage some of the more sensitive parts. Better to be safe than sorry.

If there is a case fan attached to the panel, trace the wire from it to its source. Firmly grip the connector, and move it slowly from side to side. Simply yanking could damage the wire or the pin connectors. Remember where you pulled it from, and set the paned aside.

ATX or BTX

Look at the side of the power supple next. Search for a three digit number with a “W” beside it (650W for example). It should also have ATX or BTX somewhere on it. Then, look for the cable which connects to the motherboard. There will be two of them, but you’re looking for the bigger of the two. Gently press the release on the side of bigger connector, and pull it free. Next, count the number of holes in the white connector. It will have either 20 or 24. (Computers more than two years old will almost certainly have a 20 pin connector.)

Did you buy a New power supply yet?

Now it’s time to look for a power supply. The best option for you is to search the internet, and to go ahead and buy a 24 pin power supply. You can purchase a converter which will turn the 24 pin into a 20pin. Next, decide if you’re going to add more devices to the computer. A 350W to 450W power supply is cheap, but they usually won’t have enough plugs to power more than four devices. Also, if you plan to upgrade in the future, you’ll need the extra wattage. So go ahead and buy that 650W supply.

Another aspect is that you need to figure out what type of hard drive you have. EIDE use one type of plug while SATA uses another. Also, if you have a PCIe video card, it may also need to have a plug for it.

Now about the Hard Drive

Look at the hard drive. They’re the 3.5 inch small metal device secured in the slots on the front of the computer. If they have a long, slender connector, they’re an EIDE drive. Look for something like: 650 Watt ATX Switching Power Supply w/ SATA Connector.

If the connector is a small, black one, the drive is an SATA. Look for something like: 650W 20 24 Pin ATX Power Supply w PCI Express & Serial ATA connectors.

Be sure to read the technical specifications for them. For a computer with two CD/DVD devices and two EIDE hard drives, you’ll need a power supply which has four twelve-inch power connectors. It might even say, “Molex four-pin power connectors.”

Be sure of compatibility

Don’t just buy the cheapest one you can find either. Chances are that it won’t be compatible, and you’ll have to spend extra money buying converter cables. A 650W power supply can be found online for as little as 23.00 USD plus shipping. Buying local will cost up to four times as much, but if you’re in a hurry, the people there can help you choose.

Once you have your power supply, it’s time to go on to the next phase, actually taking out the old one.

Gently remove all of the cables connected to the devices from the power supply. It’s also a good idea to lay the PC on its side. Be sure you have ample lighting. Since most of those connectors will only plug into one type of receptacle, it’s not as important to remember where they went.

Next, remove the four screws located on the back, outside of the power supply. They’re the ones which hold the power supply in place on the case.

Are there any parts in the way?

Finally, carefully slide the power supply out, pulling it inward. If you have a micro-ATX tower, there might be parts in the way. You’ll have to take those out if you’re to get a new power supply in. If the parts in the way look important, they probably are. Sometimes it’s nothing more than a support bar in the way. Once you get the old one out, put the new one in. Put the four screws in the back first, and then begin connecting the cables. The ends will only go in one way, so don’t worry overmuch.

Plugging in the wires is easier than you think

Once you’re sure all the plugs and wires are in their proper places (and that all your devices are plugged up), insert the power cable into the back of the power supply, plug it into the wall, and turn it on.

Wait, Wait… Yes it worked!

When the computer comes on, and your OS boots up, you’ll know that your work has paid off. The only remaining job is to turn the computer off, unplug the power cable, plug in the case fan if you have one, put all the screws and side panel back in place, and finally plug the power cable back in.