New Power Supply
My computer is making a loud noise that sounds like a fan going bad. A friend told me I should replace the power supply. Can you give me some tips on installing a new power supply?
Installing a New Power Supply
You're lucky you caught the problem in an early stage. When your power supply fails, you won't even be able to turn on your computer. So if you have a noisy fan, a burning smell, smoke or flames shooting out the back of your computer, your power supply may well be the culprit. Replacing your power supply is not expensive and if you catch the problem early, you shouldn't have problems with other components.
There are several things that can kill a power supply. In some cases, the fan gets gunked up with dirt or dust, and begins to slow down. The fan bearings can also go bad, which may be the case for you, since you're hearing a loud noise. When the fan dies, the power supply will overheat and fail. (See burning smell, smoke and flames above.) And sometimes, the circuitry inside the power supply is faulty and the unit will fail for what seems like no good reason.
If you have problems with your computer shutting down or restarting at random times, it could indicate that the power supply is going bad. And since the power supply provides juice to the motherboard, CPU, disk drives and some peripherals, you don't want to take a chance that an overheating condition or a power surge will cascade into bigger problems.
Fortunately, replacing a power supply is not rocket science. In fact, it's one of the easiest computer components to replace. And since most power supplies are relatively cheap ($20-$40 USD) it won't break the bank, either.
Removing the Power SupplyMost of the time, if you hit the power button on your computer, and nothing happens, it indicates a bad power supply. It's possible that a short in your motherboard could cause the problem, and you might want to test your power supply just to be sure. Doing so is beyond the scope of this article, so I'll leave that topic to the motivated and geeky. But there are a few "obvious" things you should check before assuming the power supply is bad:
- Is the power cord plugged into both the wall socket and the power supply?
- If you're using a power strip/surge protector, is it turned on and working?
- Look for an On/Off switch on the back of the power supply. Is it on?
- Look for a 110/220 Volt switch. In the USA, select the 110 volt setting. In Europe, 220 volts.
Even before you remove the system unit case, you can see where the power supply sits inside. Look on the back of the unit and you'll see the electrical power input and the opening for the power supply fan in close proximity.
Let's begin by removing the ALL plugs and cables that are attached to the system unit. We don't want any power flowing for this operation. Next, open up the system unit case. Unfortunately, there are quite a few varieties of cases, and quite a few different ways to remove the case or access panel(s). Normally you undo a few screws and either the whole case or the side panels slide off. You may need a phillips screwdriver, but that's the only tool required to replace a power supply.
Once the case is open, your next task is to identify the power supply - a metal box with colored wires that connect to the motherboard and other components. (See photo above) Disconnect all the connectors that run from the power supply to the components inside your PC. A gentle squeeze and a tug should do it. Sometimes the little plastic clips on the side of the connectors need to be coaxed a bit, but you won't need a crowbar or vicegrips. I suggest you make notes so you can remember all the components that need power when you're installing the new power supply.
The power supply unit is connected to the case with mounting screws. Remove those screws and gently side the power supply unit out. Do not use force. If some other parts of the computer obstruct the removal of the power supply, it may be necessary to remove them also. Remember to keep all those little screws in a place where you can easily find them.
Purchasing a New Power SupplyMost power supplies available today are of ATX variety. If you have the ATX motherboard plug and ATX connector (see photo) on your power supply, that's good. If you have the older AT style power supply, it will have different connectors, as will the motherboard. The presence of an AT power supply should tell you something else... your computer is an antique, and you should probably replace the entire thing instead of just the power supply.
If you're not sure what kind of power supply to buy, or how many watts it should have, refer to the manual for your computer or motherboard. Most computers will work well with a 400-500 watt power supply. If you have a heavy-duty gaming system, extra drives, or scads of USB peripherals, you may need more wattage. Check the power supply you just removed, and upgrade by a 100-200 watts if you want to be cautious. I've never shopped for a power supply by brand, but you can always do a little Googling to see if a particular unit is praised or panned by others. Tiger Direct is a reputable component supplier where you can order online. You can also find power supplies at most electronics stores.
Installing the New Power Supply
Now you have a shiny new power supply and an empty space in your system unit waiting to be filled. All the power is off, right? Take the screws you carefully saved when removing your old power supply, and use them to bolt the new power supply into place. Now follow these steps:
- Find the ATX power connector and firmly plug it into the motherboard's ATX receptacle.
- Now plug the power connectors into the hard drive, cdrom drive, and all other components that were previously plugged in to the power supply.
- Make sure that there are no unused power connectors hanging around in the case where they could touching a fan or heat sink. You can use a rubber band to keep them in a safe place if needed.
- Put the system unit case back on.
- Reconnect the monitor, keyboard, mouse, speakers, etc.
- Check the On/Off and 110/220 switches (if present) on the back of the power supply to make sure they are correct.
- Connect the power cable to the back of the power supply and plug it into your wall socket or power strip.
Hopefully your system will now power up normally, with a nice quiet fan. If not, see the notes above about burning smells, smoke and fire. :-) Have you replaced a power supply? Share your tips with other readers here.
This article was posted by Bob Rankin on 25 Oct 2007
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Article information: AskBobRankin -- New Power Supply (Posted: 25 Oct 2007)
Copyright © 2005 - Bob Rankin - All Rights Reserved