While it's unusual, every once in a while we'll find that a case switch has gone bad. It's unusual because there really aren't many moving parts with an ATX case switch that can go bad. With that said, it does happen. This tutorial will explain how to diagnose a problem ATX case switch.
Once installed, a motherboard is difficult to gain access to. There are cables, drives, fans, memory and other components that make troubleshooting the switch difficult. While you can keep most of these components in, we recommend at least removing any IDE cables that make it difficult to see.
This image shows the lower right section of the motherboard. The grouping of pins are where the case interfaces with the motherboard. There will normally either be one solid grouping of wires, which is common in major brand PCs. But in custom computers you will usually see numerous wires, some labled HDD LED, Reset SW, Speakers, PW Switch, etc... Refer to your motherboard manual when connecting these.
We have removed all of the wires to demonstrate how to jump the pins that start the PC. Look for the leads that indicate PW Switch or Power SW and remove them. This will expose two pins. Touch the tip of a flathead screwdriver to these exposed pins and you will normally be able to start the computer.
If the power supply or motherboard is bad, the PC will not start. This technique is often only used when troubleshooting a case switch or benchtesting a computer that does not have a case.
Be sure to excercise extreme caution when poking around inside of a PC with the power connected.
Resolution Summary:
Bypass a case switch to rule out problems with a motherboard or power supply
Locate the PW Switch pins on the motherboard and short them with a flathead screwdriver.
