How do I fool my old power supply to come on without being attached to a motherboard. I am trying to recover data from an older hard drive. I have jumpered it to slave, and have a new computer to plug it into. However the new computer power supply plug does not match the old big molex type connector on the old hard drive. I do have an extra power supply that will connect, but without a mother board it won't power up. I suspect there is a way to jumper pins on the large 20 pin power supply connector to turn on the power supply. Any one know the correct pins?