I found a person asking this question over yahoo answer, how to turn on a computer without using power button?
As an IT engineer, I use this method since five years ago when I learn how to assemble a computer on my 1st career. Most people sure curious how to turn on a computer if without power button? This is not difficult, as long you have some technical knowledge over the motherboard and able to identify the power switch location.
Please bear in mind, do not test this if you do not have any basic technical knowledge or consult some professional before you do it.
Most of the motherboard have a sticker like above. The PC assembler has to stick this sticker behind the CPU casing, you can find this sticker around the CPU casing. This sticker indicates the location of the power switch in my motherboard.
The power button, Reset button, Hard Disk LED, and Power LED on the casing all are connected to this section. Most people found that their power button spoil, or broken, they will have difficulties to turn on their computer.
See the above picture, the power switch (SW), reset switch (SW) and etc, all this are connected to the motherboard from the power button, a reset button over the casing. When you see closer to the switch (SW) you can see it connect into the motherboard, the SW will insert and connect to 2 metal pin in the motherboard.
In the easy way to describe, when you press the power button, this 2 pin will be electrically connected to each other, and send the motherboard a signal to power on the system.
To start the computer without using the power button, take out the “Power SW”, make sure you identify which 2 pins belong to the power button (refer to the label behind), use a test pen or any metal surface to touch the two pin, it won’t have any electric spark, just allow the electrical signal from 1 pin send to another pin, your computer will start without pressing any power button.