WARNING: I don't know if there is a connection to a problem I just had, but turning this feature on was the last thing I did before heading to bed last night.
My computer is only a few months old. I leave it on all day/all night. It is set to go into power-save mode after 30 minutes. Its been doing it each night with no problems for months. In the morning, a shake of the mouse wakes it up.
THIS morning, nothing would wake the monitor to life. The monitor power button was orange. Turning it off, then on again, would make the button turn green, screen would display "entering power save mode", go black again, and the monitor button would go orange. Pressing any keyboard buttons wouldn't wake it again. (Its not the monitor that has a problem.)
Luckily, I have a laptop also & was able to google "can't take monitor out of power save mode". I found several people with the same problem in the first google result. The solution for many was to replace the motherboard battery. While I haven't done that yet, since its morning, I find that hard to believe as my problem for a computer that only a few months old. If it persists, I will try it obviously.
For now, after holding the computer power button to be able to turn off computer & reboot, that worked. First thing I did was turn off that screeensaver I had turned on last night. Coincidence? I don't know.
Just thought I would throw it out there if it happens to someone else who has computer set same as mine with power save mode turned on.