How to turn off your monitor

# Monitor output
# Controls if HDMI PHY should output anything to the monitor
setenv monitor_onoff "true" # true or false

# Boot Arguments
setenv bootargs ${bootargs} monitor_onoff=${monitor_onoff}

[system] -> [preference] -> [look and feel] -> [Screensaver] 
[Power Management] tab in the bottom area of this menu

For example, if you set screensaver time to 1 minute and display off time to 5 minutes in Power Management tab,

- in 1 minute, display will be turned off and screensaver is activating but, monitor is still alive.

- in 5 minutes, monitor will be turned off.

The env description, “suspend_hdmiphy” is included in boot.ini as following.

You should set suspend_hdmiphy to 'true' or '1' to activate monitor off option.

# Monitor on/off option
setenv suspend_hdmiphy "true" # set "true" of "1" to activate monitor off option

# Boot Arguments
setenv bootargs ${bootargs} syspend_hdmiphy=${suspend_hdmiphy}

You can set the standby time to enter sleep and monitor off using display setting menu. For example, if you set the sleep time to 5 minutes, your monitor will be turned off in 5 minutes.

[Menu] -> [Settings] -> [Device] - [Display] -> [Sleep]
Set sleep time

And then, please turn off Daydream option.