How To Guide 4Windows

How to Troubleshoot a Computer That Won’t Power On

The most horrifying problem that you can encounter in a computer is to see that your computer does not power on. I mean by does not power on is that your computer is dead, the Power and HDD LED don’t light up, you don’t hear any sound from the FAN inside your computer, you don’t hear your Hard disk drive spin and no display on your display monitor. The first thing that may come up to our mind is that there is a hardware failure and most probably the computer power supply is the faulty hardware that causes this.

Before we come to a conclusion that the power supply is the cause of the problem we have to consider other factor that might cause your computer not to turn on such as power plug or probably a short circuit inside your computer. The tips and techniques I’m going to share you is based on my experience as a computer repair technician and I’m doing this technique for more than 15 years in the field . The troubleshooting method I’ll cover here is only for power related and does not cover the error messages when loading windows.

Troubleshooting tips for a computer that does not power on.

Before you try to open your computer casing, first is to have an external visual inspection of your computer. You should first check the following before proceeding to the next step.

  1. Check that the computer power cable is plugged-in properly in to the socket of the power supply of your computer.
  2. Check that the Automatic Voltage Regulator (AVR) or your Uninterrupted Power Supply (UPS) is powered on and connected to a 110/230V wall socket.
  3. Check that the power wall socket is working and delivering the correct voltage of 110V or 220V depending on your country voltage standard.
  4. If your computer power supply have power on switch, check that the power on switch of the computer power supply is switched on.
  5. Check that the power cable going to the power supply is in good condition and doesn’t have a tear or wear, sometimes rodent do love to eat wire robber such as power cords and the wire inside the cord do break .
  6. Check that your monitor has power on it.
  7. Check that the power button on the front panel of your computer is working properly and is not stucked or defective.I have experienced before when somebody ask me for an assistance to check his computer because his computer doesn’t power on and just to find out later that the cause is just the power cord not properly inserted to the wall socket.With all the external inspection done and nothing happens then it’s now time that we open the computer casing, to do this you just have to unscrew the two screws at the back, the left side of your computer casing.

    When you have opened your computer casing, the first thing to do is to touch any metallic part on your computer casing to discharge any static from your body. The next step is to remove all of the add-on card or peripheral devices attached to your motherboard such as your Ethernet card, sound card or any other devices attached to your motherboard except the memory and the processor with the heat sink. Sometimes add-on cards when defective drain too much power from the power supply that causes the power supply to shut down or even causes short circuit that shut down the power supply. Please always bear in mind that every time you remove any add-on card or peripheral devices on the motherboard always make sure that the power cord is removed from the computer power supply to avoid any damage to the motherboard or other peripheral devices and also to yourself. Now that you have removed all peripheral devices try powering on your computer, don’t forget to reconnect the power cord to your power supply. Is your computer working now

    If YES that’s great, one of the add-ons or peripheral devices are causing the problem try inserting the peripheral one by one so you can see which add-on device is causing the problem, don’t forget to unplug the power cord when inserting any add-on card to the motherboard. Remove permanently or replace the defective add-on card. Congratulation you have fixed your computer.

    If NO, then we have to check the power supply it might be defective, check computer power supply for more info. Remove all power connector from disk drive, floppy, optical drive, atx+12 volt power connector and the 24-pin atx power connector. To test the power supply using a paper clip hold the 24-pin atx power connector and locate the green wire and a black wire, the green wire is usually located at pin 16 and the only green wire on the connector, check out 24-pin atx power connector for more info on pin configuration. See the illustration below on how to short the two pins.

    power_supply_test_loShort circuit Pin 16 and ground using a paper clip or any stranded wire as shown, the power supply fan should spin normally. If the fan didn’t spin you can say right away that the power supply is at fault and must be replaced with a good power supply, you can also connect one molex connector to the optical drive or hard disk drive to see if it power up. If the fan or the drive you connected powered up then the power supply could be good, you can also check the voltage output using voltmeter. If the power supply is in good working condition you can now return all the connector to its respective point in the motherboard where it was previously connected.

     The next step would be to look for the front panel connector a 20 pin panel connector on your motherboard as show below, with all the power connector connected to your motherboard plugin the power cable on your power supply and momentarily short circuit the two pin labeled PWR and ground as shown in the image, short circuit should not be longer than 2 seconds. By doing the short circuit technique will bypass the “power switch on” button on your computer front panel because this pin is where your front panel power on button is connected. Check your motherboard user manual to find out the location and diagram of your motherboard front panel. When you have short circuit it, the system should power up when this happen then the culprit is the power on button on your front panel. You can also do this technique before you remove any add-on card or peripheral devices as stated in the previous step, if you would like to check the power button switch first.


    Now that you have found out the cause of your computer problem all you have to do now is to replace those defective parts with a known good part.


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