Hi and welcome to Geeks to Go. You verified the power supply is ok by putting it in another computer so that rules it out as the problem. Do you have a reset button on your computer? These are generally on the front, a small button that needs to be pushed with a pen or pencil to reset. On my computer, this is located directly below the power button. Have you tried resetting that? When you try to power up, does any thing at all light up or spin (fans)? Do you see any LED's light up on the motherboard? Post your system specs when you reply as this will better enable folks who want to try to help you.