Automatically Shut down and Power up your computer : 

Restore on AC/Power Loss

Picture of Restore on AC/Power Loss

Set the computer to power up when power is lost.  You can do this by entering the computers BIOS setup and looking for Power Management settings.  On most computer you will see "Restore on AC/Power Loss".  Enabling this will allow the computer to power up once house hold power is established.  An example would be: Your power goes out for a moment...when the power comes back on, your computer will automatically power up.  You want to "Enable" this feature, then Save & Exit the BIOS. Once saved, go ahead and power down your system.