Computer Monitor Energy Use

Computers - General	Setting Up A Computer	Computer Monitors
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The simplest ways to reduce the power used by a monitor are to switch it off at the mains when not in use and turn the brightness down as far a possible consistent with an easily readable display. Minimising the ambient light, whether natural or artificial, means lower brightness levels are effective.

There are two main types of monitor in use with computers, the original CRT type which are disappearing fast and the newer LCD type which have a lower power consumption. In order to bring some sense to some of the power consumption myths surrounding monitors a number of tests were done on an LCD and a modern CRT monitor of similar size using a similar set up on the same computer. These tests were done in 2008. The details of the two monitors used are:

CRT Monitor

AOC 17” Spectrum 7Vlr made in China (manufactured February 2007)
Set to 1280*1024 resolution 60Hz refresh
OS: Windows Vista Business
Computer: AMD Athlon 3.2GHz, 1GB RAM

LCD Monitor

Samsung 17” Sync Master 710N
Set to 1280*1024 resolution 60Hz refresh
OS: Windows Vista Business
Computer: AMD Athlon 3.2GHz, 1GB RAM

The results are set out below:

Test	CRT Monitor	LCD Monitor
No signal (display blanked) - Standby	4W	2W
Standard Vista Desktop (12 Icons)	72W	24W
Black background (all windows minimised)	65W	24W
Black background + 1 window (open windows white background, black text file 50% screen)	72W	24W
White background (all windows minimised)	79W	23W

From these results when comparing like for like:

LCD monitors use significantly less power than CRT ones in all modes of operation.
Even when in standby the LCD monitor uses a measurable amount of power.
With CRT monitors the darker colours use significantly less power.
WIth LCD monitors the darker colours use slightly more power.
To achieve the maximum savings with either type don't use a screen saver and blank the screen when the computer is idle.
Switch of monitors at the mains when not in use.

An alternative to using dark backgrounds with CRT monitors is to use a utility like CRT Saver which blanks the background.