virtualbox.org

I need to test some power save mode features and I changed the power save mode of windows to turn off the monitor after 1 minute and to sleep after 2 minutes, but it seems not to work, the virtual box just "turns off" the display after 10 minutes of inactivity.
I'm changing it in the wrong place in the windows configuration or it something that doesn't work in a virtual box, and the virtual box uses it's own "power save" system?

VirtualBox doesn't turn off anything by itself, it just immediately obeys the command of the guest OS. So, if the (virtual) display is turning off after 10 minutes then I guess that's what your guest OS is configured for.