Check your mobo manual if you have it, there is a jumper you can move to bypass the start-up switch. This way, you can use the power to start it up, and this will let you know if the switch is bad. Newer motherboards (last few years) always have a 5-volt charge to the mobo to keep certain things going. So in actuality, the "switch" on the front of the case is nothing more than an in-between that signals for the CPU to receive a "power good" message, thus causing the CPU to start the boot process and accessing the system BIOS to start the POST process.