What to do with free server resources?

Question

Network administration

A server is rented for the site, the processor load on it rarely exceeds 10%.
What can be done with the rest of the resources so that it does not stand idle and, perhaps, partially pays off? Now BOINC operates there with the World Community Grid.

Answer 1

Change to a server without excess resources.

Answer 2

If the server is outside the rush, then raise the VPN service and promote it

Answer 3

Serve hosting vps vpn and other services