Ensure that nothing overwrites the settings, e.g. xscreensaver, xfce4-power-manager or anything else. I set up Section "ServerFlags" Option "BlankTime" "0" Option "StandbyTime" "0" Option "SuspendTime" "0" Option "OffTime" "0" EndSection by xorg.conf and then use xscreensaver-command or xfce4-power-manager-settings or xset dpms force && xset to set up the wanted values, when the CRT-Monitor should go to sleep. For my openbox Arch Linux I use xfce4-power-manager. [rocketmouse@archlinux ~]$ xset q | grep -A2 "Screen Saver:" Screen Saver: prefer blanking: yes allow exposures: yes timeout: 540 cycle: 0 [rocketmouse@archlinux ~]$ xset q | grep -A3 "DPMS (Energy Star):" DPMS (Energy Star): Standby: 600 Suspend: 0 Off: 3000 DPMS is Enabled Monitor is On The monitor is turned off after a while. However, I have different Linux installs and IMO xfce4-power-manager isn't the best choice. However, I have no issues with using different xfce4-power-manager or xscreensaver profiles, but I'm lazy, so my momentarily scripts aren't a pleasure to read. Maybe this does help: [rocketmouse@archlinux ~]$ cat .config/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml <?xml version="1.0" encoding="UTF-8"?> <channel name="xfce4-power-manager" version="1.0"> <property name="xfce4-power-manager" type="empty"> <property name="dpms-on-ac-sleep" type="uint" value="10"/> <property name="dpms-on-ac-off" type="uint" value="50"/> <property name="show-tray-icon" type="int" value="0"/> <property name="blank-on-ac" type="int" value="9"/> <property name="presentation-mode" type="bool" value="false"/> <property name="general-notification" type="bool" value="false"/> </property> </channel>