Look into the carnetix P1900 power supply as it offers 18v,19v,20v which most notebooks expects. I have my Carnetix P1900 ACPI relay contact wired to my power switch, so now it powers up and powers down my notebook with the turn of ignition key.

If you don't want to open up your notebook, you could see if Wake On LAN works for you. This can be used to turn on your notebook. Turning off is simple, just use windows built in power options.