How to Fix Your Own Computer, Will Not Turn On

by fliptop 04/19/2010

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Now that your toolkit is ready, it's time to tackle the first problem - when the computer won't turn on. By this I mean it won't power up, not that it doesn't boot up after turning on.

Problem - Computer will not power up or turn on

No matter what you do, no matter how many times you press the on/off switch, your computer stays off and will not turn on and none of the LEDs are lighting up.

Possible causes

This problem may be caused by several things:

• There's no power coming out of your wall socket.
• The power cable is bad.
• The 0/1 switch on the back of your power supply is set to 0.
• The power supply in your computer is bad or not supplying enough voltage.
• The power switch on your case is malfunctioning.
• You have a bad motherboard, CPU, ram or other component in your computer.

Possible Solutions

1. Test your wall socket. - Use your volt-ohm meter to make sure you have sufficient voltage being supplied by your wall socket. You can also plug in a lamp to make sure there's power (if you don't have a volt-ohm meter).

2. Test your power cable. - You can use your volt-ohm meter to test continuity on your power cable, or use the cable on another device that's know to be working. For example, lots of monitors use the same power cable as your computer, so try plugging in your monitor and see if it gets power.

3. Check the on/off switch on the power supply. - Look at the back of your computer case, near where the power cable plugs in. On some power supplies there's a switch that has a 0/1 on it. This switch needs to be in the "1" position for the power supply to work.

4. Verify your power supply is not malfunctioning. - If you don't have a volt-ohm meter, you can test for a bad power supply by either a) replacing it with one that's known to be working; or b) unplugging all peripherals (hard drives, CD/DVD drives, floppy drives, PCI and PCIx cards, etc.) from your motherboard and trying to power it up again. Sometimes when a power supply goes bad, it will supply enough voltage for just the DVD drive, but when you plug in the hard drive it gets overwhelmed and stops providing power. If you're replacing your power supply, be sure to use one that's rated for use in your computer. For example, if you have a heavy-duty gaming machine with dual video cards, you may need more than a standard 350W ATX power supply to provide enough juice for your cards.

   If you have a volt-ohm meter, you can test the output connectors for sufficient voltage and replace the power supply if necessary.

5. Test continuity on your power switch. - If you look at the motherboard inside your computer case, the front panel LED lights, reset button and on/off button should all be connected to the motherboard in the same place. Pull off the power switch wires (they should be labeled on the motherboard connector) and use your volt-ohm meter's continuity tester to see if the switch is working. If it's not, you can test to see if it will turn on by shorting the power switch's connectors using the flat-head screwdriver. If everything else is working as it should, when you short the connectors the computer should either power on or off. Note that "off" may require shorting the pins for 4 seconds or more.

6. Your motherboard or other critical component is bad. Most modern motherboards will not allow the computer to turn on when they sense there's a problem. This is done to prevent further damage to other parts of your computer. A bad CPU or RAM may cause this problem. If you have all your devices unplugged from both power and the motherboard (hard drives, CD/DVD drives, floppy drives, any other PCI or PCIx cards) so that only the CPU and RAM are connected, and it still won't turn on, then you should look into replacing the motherboard, CPU and RAM.

   Without having another nearly identical system to test the CPU and RAM on, it's safe to assume that, after trying all the other troubleshooting steps listed above, your computer has bad components that are prohibiting it from being used. Best to upgrade at this point!

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