Power Supply FAQs

| December 6, 2010 | 7 Comments

The power supply (PSU) is part of the computer many think of as the case because they come with a lot of cases.  It is its own separate component, though. Your computer power supply is responsible for providing your motherboard and other components with very specific DC voltages in ranges of 12V,-12V,+5V,+5VBs and +3.3V. If those voltages fluctuate, your computer may not boot or become damaged. So having a quality PSU is as important as having a fast processor. If the power supply goes bad, you should not attempt computer power supply repair, as a PSU is inexpensive and easy to replace.

computer power supply

My power supply fan isn’t moving. Can I replace it?
You can if you have experience working with a soldering iron, but we advise against it because the fan may not even be the source of the problem. It’s also dangerous. You can easily replace the entire PSU for very little money.

Our computer’s power supply has failed. What type should I get?
You’ll probably find your power supply is a standard ATX power supply with a single 20-pin connector to the motherboard. You should replace it with one of equal or greater wattage. Spending more on a power supply with greater wattage will not improve performance, just allow you to run more devices. Look for a name brand like Antec or Thermaltake.

Is there any easy way to test my power supply?
Many local PC and electronics stores will sell stand-alone power supply testers for about $12 USD. All you have to do is plug the power supply into the adapter and turn it on. The device will instantly tell you if the power supply is bad. If you have a multimeter, you can also test the voltages.

Why can’t I turn off my computer when it crashes? I have to use the power supply switch on the back.
Try holding the front power button for five or six seconds. Merely pressing the button will not turn the PC off, as this isn’t a spring-loaded switch that has an On and Off. By holding the button for several seconds, the computer knows to shut the the power supply down.

I just installed a new device. Does it matter which power plug I use?
No. You’ll notice that your power supply has several plugs not being used. As long as it fits, it’s okay to use. There may be a couple of odd connectors that go to the case fans or floppy drive, but any of the 4-wire plugs can be used for devices such as hard drives, CD and DVD drives, case fans, etc.

What is the difference between a modular and non-modular power supply? A modular power supply is a type of power supply that has removable cables. Non-modular power supplies are hard-wired with cables, whether you need them or not. A modular power supply give you the ability to have a clean case interior with improved air-flow. See an example of a modular power supply here.

Category: Hardware

Dave

About the Author ()

Dave has been providing free computer repair and tech support advice online since 2002. Join us on our forums and be sure to subscribe to our newsletter for weekly tips and other helpful computer articles. Connect with me on: Google+

Comments (7)

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  1. Jai says:

    Can I return the power supply if I found out that it is not the problem with my pc? Because everytime I plugged in the power cord, it automatically powered on without pressing the power button on my case. And, it says no signal on my monitor.

  2. dave says:

    how to repair not function power supply?

  3. SAM says:

    I HAVE REPLACED MY POWER SUPPLY, BUT WHEN I SWITCHED ON MY
    PC THE HARD DRIVE GREEN LED IS LIT BUT POWER RED LED IS FLASHING CONTINUOUSLY. WHEN I PUSH FRONT SWITCH ALL FANS WILL START AND WILL STOP IN FEW SECONDS. PLEASE COMMENT YOUR SUGGESTIONS ON THIS SO THAT I WILL SOLVE THE PROB.

    THANKS

    • What size power supply was previously in the case? What size is in now? Did the symptom change once you replaced the power supply? If not, maybe the problem is with the motherboard.

  4. Alex Davidson says:

    I have a viao laptop that i bought in 08 from Fris. One day when I tried to turn it on I got nothing the power pack light was lit up but nothing other than that. When I took it back they told me that they didnt know and I would probably be better off just getting a new one. My question is would it be worth the time and money to get it repaired and updated or not. Thanks Alex

    • The laptop is not that old and it might be a simple fix. If you like the laptop, you might want to take it to a different shop. It might simply be a solder job on the power jack. But even if you have to replace the motherboard, it should still be cheaper than a new laptop.

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