I think one of us is asleep at the keyboard... but here is how I would "invoke power save on monitors"...
....I would set the monitor to "OFF" mode....
.... and when I needed it again, I would switch to "ON" mode...
Does that help you?
(ok-- here is what you are looking for--- right click on the desktop----->properties---------->screen saver tab, make your selection)
But "OFF" mode invokes power save much faster... and will probably save an additional 5 watts...