I have noticed that a Poweredge T300 (with two redundant PSUs) drains when turned off (but still plugged to the wall) 14 watts per PSU, and the heating of the PSUs is significant.
ps: Yes, I know they are designed as severs and therefore should be always turned on, and bla bla bla
If you don't want the server to use any power then unplug it. The system will use power when it is plugged in because there is hardware that can still function when the system is powered off.
Daniel MysingerDell EMC, Enterprise EngineerGet support on Twitter @DellCaresPRO