The problem you are having is the exact opposite of what I was having. I didn’t want power turned off on my monitor. I only wanted the screen saver to kick in after 10 minutes of inactivity. But nothing seem to work for me. I learned that there is a power managment appilcation for Yast2, and I just used the default options. There are other options that can be used for your situation. But this took care of my problem and maybe it can take care of yours. Hope this helps.