XP has scrnsave.scr which is a "Blank" Screen saver.
I am aware of that screen saver.
When I use it, my monitors do go "black" but not 100% black.
More like 98% black and all my "pixels" are "black" but they are sent red-green-blue data to EMIT a "black".
Whereas using POWER SCHEME turns the monitor OFF, no red-green-blue black-emit but truly OFF.