The life span of a computer monitor depends on the type of light source it uses and how many hours the monitor is used per day. The two most popular monitors in use as of 2010 are cathode ray tube (CRT) monitors and liquid crystal display (LCD) monitors.
Cathode Ray Tube Monitors
CRT monitors are rated for approximately 25,000 to 30,000 hours of use. If you use the monitor eight hours a day, it will take eight to 10 years to reach 30,000 hours. A CRT monitor uses an electron gun inside a vacuum tube to shoot electrons towards a fluorescent screen. These monitors are generally deep, fragile and heavy.
Liquid Crystal Display Monitors
LCD monitors are typically rated for 30,000 to 60,000 hours of use, which amounts to 10 to 20 years if you run the monitor eight hours a day. These monitors have a flat screen and use a liquid crystal solution between two sheets of polarizing material for their light source.
Turn your monitor off when you're not using the computer to extend its life span. You can also use the "Standby" and "Powersave" features of your monitor to prolong its life. These features turn off the monitor's light source when it's not in use.