The requirement for BOINC to run under a logged-in user account to be able to access GPU and VirtualBox resources will lead to a lot of CPU idle-time after a reboot, unless the user is present.

To work around this, without compromising security too much, I have set my computer to auto-login and then lock the screen. In case it is useful to others, here's what I did:

* reinstalled BOINC so it is no longer running as a service
* removed the requirement for a password at the windows login screen: Start > "netplwiz" > uncheck "Users must enter a username and password..."
* installed "Auto login and lock" which automatically locks the screen immediately after the first login.

It isn't ideal but seems to work. I'll keep testing it.

https://www.softpedia.com/get/System/Launchers-Shutdown-Tools/Auto-Logon-Lock.shtml

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