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So, is this true?

Screensavers with graphics and sound effects will drain the power more quickly, whereas a blank screen will conserve power.

And if it is true, how much more battery power/time do I get if I have the laptop idling for 30 minutes with a sparse screensaver versus a static display of the last document I edited?

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This seems like a great opportunity for an experiment! –  larsks Jan 11 '11 at 21:33
    
I agree with larsks, however, it would also depend on what color the blank screen is. White uses more power than black, which would throw an experiment off, so sticking with the default black blank screen would be interesting. –  Paul Jan 11 '11 at 22:14
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5 Answers

up vote 10 down vote accepted

Is it true? Yes, doing nothing uses less power than doing something. Displaying nothing uses less power than displaying images, which requires accessing the hard drive to get the images or using the GPU or CPU to generate 2D/3D images. Turning pixels on and off uses power. Not a lot, but more than nothing. Speakers need power.

What difference would you notice between a blank screensaver and just leaving the display on? Compared to just having the desktop displayed, probably a negligible difference in power consumption. Beyond that it depends on what application you're running.

Screensavers are for saving your screen, not conserving power. If you want to save on power disable the screensaver and set your display to shut off instead. Turning off the LCD backlight saves a lot more power.

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Once upon a time they were for saving your screen, but it hasn't been that way for over 10 years now. These days we have DPMS to power the screen off entirely when the system is idle, and LCDs do not suffer from burn in anyway. They only seem to remain in use for the entertainment value. –  psusi Jan 15 '11 at 20:05
    
@Psusi not exactly true on LCD burn... I've seen a few that have "slightly" burned. –  KronoS Jan 28 '11 at 23:34
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Rendering graphics is an intensive task for any CPU, so it will definitely use more battery than just showing a black screen.

The same applies to playing sound. Compressed sound files need decoding, which uses CPU time as well.

Saying how much energy you will conserve is however a very difficult task and can't be done with easy methods, as far as I'm concerned.

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From your specific comparison, screensaver vs static doc, I'd say you would never see a difference. Most screensavers won't use much CPU. Remember that you have a lot of background processes, the screensaver may not use disk, but your word processing app may do background saves. As others have said, you're much better off making your display turn off. No matter what is displayed on the screen, your backlight is still on.

If you really care, I'd buy/borrow a Kill-A-Watt. http://www.thinkgeek.com/interests/giftsunder20/7657/ Take the battery out of your laptop, run the laptop on mains power. Compare the two. I'd doubt if you'd see any difference. There's too much background noise on a modern OS to compare the two.

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Yes and no.

A graphics or calculating screen saver could definitely drain power quicker since the processor, RAM and perhaps even the HDD are working harder. As for sound, powering up speakers definitely uses more current and more then many components.

As for MOST screen savers, the amount consumed extra is negligible.

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d-e-f-i-n-i-t-e-l-y.com –  BloodPhilia Jan 12 '11 at 0:30
    
:| My speling is aweful. –  Jeff F. Jan 12 '11 at 0:32
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An online blog distinguished between mobile devices that use backlit LCDs and OLEDs:

OLED screens don't have a back light. Instead each pixel is an Organic Light Emitting Diode that makes its own light. That means reducing how many pixels you have on during regular use of your phone can have a big impact on battery life. That doesn't just mean changing your wallpaper. You could also look at alternative apps that have dark themes.

http://blog.stevemould.com/phone-battery-save-black-wallpaper/

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