Select the settings you want:
Screen Blanker: Enables (On) or disables (Off) the screen blanker immediately, even before you click OK. When Screen Blanker is On the Start Blanker slider is active.
Start Blanker: Specifies the number of minutes from the last pointer movement or keystroke before the screen is blanked. When this value is changed, the new value goes into effect immediately, even before you click OK.
To save the changes, click OK. To return to the default settings, click Default.