How to Replace a Dead Power Supply

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Hey My Computer Won’t Start!

I recently had a service call from a local church, where one of its computers would not power up. When they would press the power button the power light would come on, but the computer did boot up, not one sound.

If you are familiar with computers, then you know that when the power button is pressed, you should be able to see the computer go through what is called a POST which is short for Power On Self Test. This is where the computer goes through a process of starting all of the hardware and checking that it is in working order.

If there is a problem with any of the PC components (parts), a computer program known as the BIOS or Basic Input Output System will emit a series of warning beeps. These beeps will usually indicate what the problem might be. However, when you do not get anything, nothing on the screen (no POST), no sounds, nothing is running, etc., it is more than likely a power issue.

What is a Power Supply?

Your power supply is the component that powers your devices in your computer. It powers things like the hard drive, CDROM and CPU. There may come a time when you have to replace it. Symptoms of a power supply going bad can include random reboots; random crashes the computer not starting at all. When replacing your power supply there are a couple of thing to take into consideration.

Choosing the Right Power Supply

The most important thing to do is to get the right one for your computer. Your computer will most likely use the ATX form factor. You also need to make sure you get a power supply with enough power for your computer’s hardware. A 300 to 500 watt power supply is sufficient for most computers. One way to ensure that you get the right one is to just check the wattage on the bad or dead power supply.

Selecting a power supply that has more wattage than your current one is not a problem, just don’t over-do it. However, if you buy one that is rated at a lower wattage, it may not be powerful enough to power all of the devices in your computer. So don’t do that, don’t be cheap. Make sure the power supply has enough power connections and the right types of connections.

Listed below are the connections of the modern day power supply:

* 20/24 Pin Motherboard Connector

* 8 pin +12V Motherboard Connector

* 4 Pin +12V Motherboard Connector

* 4 Pin Molex Connector

* 4 Pin Floppy Connector

* 6 Pin PCI Express Connector

Replacing the Power Supply in 5 Easy Steps

Replacing the power supply is a pretty easy job. Just make sure you unplug the power cord first!

Step 1 – Open the case and remove the power connections from the devices and motherboard. Make sure you note how each connection fits

Step 2 – Using a screw driver, remove the four screws holding the power supply to the back of the case

Step 3 – Carefully remove the old power supply, being careful not to bump any components on the motherboard. You may find that you have to remove a PC device inside your computer in order to get the power supply out.

Step 4 – Installed the new power supply and re-connections in the same way you remove them.

Step 5 – Once everything is re-connected test your work by turning on the computer, do not place the computer cover back on until you have ensured everything is working. If all goes well, your computer will power up just like it did before the power supply died.

Congratulations! You have just installed your first power supply.


  1. John
  2. John

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