Remote Shutdown a Non-Network Computer?

So long story short, I have access to my friend's IP adresses through several servers I host which he plays on, servers which he idiotically griefed to the ground. The problem is, I don't know how to use these IPs to shut him down as a search on this subject only brings up ways to shutdown network computers. So what I'm asking here is if anyone has a way to shut his pc off using only his IP?

Google metasploit, i think its a function that allows you to run commands on your friends computer through backtrack 4 or something like that. Im not very sure as i am still learning.