Power Supply Repair FAQ

Below you will find answers to some of the most common questions we are asked regarding diagnosing power supply issues and repair.

1. My computer has a 20 pin motherboard connection and the power supply I
received has 24 pins. Will this still work?


Answer: Yes, our 24 pin power supplies can support both 20 and 24 pin
motherboard connectors. The 24 pin connector is actually two pieces. If you
have a 20 pin motherboard, just disconnect the additional 4 pins on the
power supply connector and leave to the side as you will not be using those
pins on your motherboard. To do this, you hold the rectangular connector
between your fingers. On some connectors, it slides off. On others, you just
pull it off.





 

 

2. My original power supply had a white wire on the large motherboard connection. What is this for?

Answer: The white wire represents the -5V rail and was used for the old ISA
standard. ISA has not been used for nearly 10 years so you most likely do
not need this wire. Most power supply manufacturers omit this wire in their
wiring as ISA is obsolete. Some still leave it in as a place holder. The
different colored cables in the large motherboard connector designate
different voltage rails that the power supply outputs to power devices in
your computer system. For example, in standard ATX wiring, an orange wire
represents +3.3V rail, yellow wire represents the +12V rail, and a black
wire represents a Ground. For example, if the video card in your computer
uses the +12V rail and the +12V goes out. Your video card, as well as any
other device that uses that rail will not work.

3. My computer is not turning on. What is normally the cause of this?

Answer: The first thing to suspect is the power supply. The power supply is the first part that normally goes out on a computer. The second most common is the motherboard. Sometimes, one can take out the other. Other parts can cause this, but those two are the causes the majority of the time.

4. My computer is turning on, but I'm not getting any video. What does that mean?

Answer: If the computer is turning on, the fans are spinning, but you're
still not seeing anything on the screen, that is can be power supply or
motherboard. Normally, there is a short somewhere on the motherboard
preventing it from properly displaying video. You can try putting an
external video card into the motherboard to bypass the onboard video port on
the motherboard if the video chipset is on the motherboard. In most cases,
however, when the video goes out that signals the motherboard is bad and
needs to be replaced. The power supply is the other part that needs to be
checked. If the power supply or one of the voltage rails inside the power
supply is not operating properly, the video may disappear. The other
voltages may work correctly, however, the rail that controls the output of
video on the screen will prevent images from appearing.

5. I thought my power supply was bad. I plugged in a new one and it still doesn't work. What is going on?

Answer: That normally means there is a short somewhere on the motherboard
preventing it from turning on. It's possible the original power supply still
works. You would need to test it to find out. Most likely the motherboard is
main culprit. It's a good idea to disconnect any non-essential devices such
as hard drive and cd-rom's to limit the variables involved in your test.
Once you have proof that a device is working, you can add the other items
back into the mix.

6. How do I prevent my computer from getting a virus or spyware?

Answer: Viruses and Spyware are normally caused by file transfer. There's no
100% full-proof method to prevent yourself from getting a virus other than
to not transfer files or connect to the internet. For most, that is not
feasible. Virus and Spyware protection software is available that goes a
long way to prevent you from getting a virus. Always practice caution when
visiting online websites and downloading attachment files through your
email. These are the most common way to obtain a virus/spyware. Protect
yourself by not visiting questionable websites or smaller websites that are
not protected. You can have one antivirus program installed on your
computer. For spyware, you can run multiple programs. Normally a combination
of the anti-spyware software work best as different ones are better at
removing the different types of spyware.

7. I thought my power supply was bad. I plugged in a new one and it still doesn't work. What is going on?

Answer: That normally means there is a short somewhere on the motherboard
preventing it from turning on. It's possible the original power supply still
works. You would need to test it to find out. Most likely the motherboard is
main culprit. It's a good idea to disconnect any non-essential devices such
as hard drive and cd-rom's to limit the variables involved in your test.
Once you have proof that a device is working, you can add the other items
back into the mix.

8. How can I test if my power supply is working?

Answer: There are 3 recommended ways to test if a power supply is working.
The easiest is to use a power supply tester if you have one available. Next
would be to use a known working power supply. Plug in a new power supply
into the motherboard. If the motherboard still doesn't boot or give video,
that means the motherboard most likely has issues. The other way to test is
called the paper clip test. First you unplug the power supply from the wall.
You take a paper clip and bend it into a U-Shape so both ends are on one
side. Then unplug all the connectors going to your motherboard and other
devices, including the large 20/24 pin ATX connector from the motherboard.
You will see many wires of all different colors coming off this connector.
You will plug the paper clip with one end into the pin with the green and
one end into the pin with a black wire. There should only be one green wire
or ignition. Please note that there are multiple black wire are Grounds so
you will have a few to choose from. You can choose any one of the black
wires or whichever one is easiest to get to as they are all the same. By
shorting these two pins, the power supply will turn on if it is working when
you plug the power supply into the wall without being plugged into the
motherboard. This eliminates a defective motherboard or other part from
preventing the power supply from turning on.


Email sales@cputopia.com for more information.