When you come home from work and sit down by the pc to check what your friends were up to during the day, or you wake up and want to check last night’s late game score; the last thing you want to experience is silence when you press the power button.  You apprehensively check the power connection, it’s plugged in and the strip is on.  So what gives? the power supply?  Not always.

On an ATX power supply the actual “power switch” is built into the supply.  However, it uses a circuit to detect when to switch on and holding that circuit closed tells the power supply to shut down.  That is the function of the “Power Button” on the front of your case.  The mechanism in these switches is usually quite cheaply made.  So what happens when it fails?  You get no power.

The button is wired into a pair of leads on the front panel connector of the motherboard.  Other items that may be connected to this panel include: the reset button, the power LED lights, the Hard drive activity light, and perhaps the pc speaker.  There’s 2 ways to test for a bad power button switch.

The first way is to take the reset switch and plug it into the power switch leads, and press the reset switch.  If it turns on, there you go; bad switch.  The other way carries a little bit of danger with it and you need to be careful with it.  Closing the switch basically just bridges or “shorts” the connection.  You can take a regular flat head screwdriver and touch it to the 2 leads and see if the pc turns on.

If you touch the wrong leads you might perform an activity known as “letting the magic smoke out” .  In this case you could fry some of the caps and you will know you’ve done this by the small trail of blue smoke immediately followed by the smell of sulfur and burnt plastic.  Needless to say this is not the outcome you desire.

So whenever possible use the reset switch.  The only 2 times it should not be possible are if you’ve already had a failed switch and you are using the reset switch for a power button, or the manufacturer put all the front panel connectors in a single plastic plug.

If you decide to replace the switch, known that you will most likely have to contact either the manufacturer  of the pc or the case to attain a perfect match.  If you do not want to do this or the manufacturer wants too much or won’t sell you one; you can go to your local Radio Shack or hardware store and pickup a momentary contact switch with 2 leads.  You might have to do some cosmetic alterations to your case though as no 2 switches ever seem to use the same mounting pattern.