Martianalix

Computers have been using LEDs for years, usually green ones to indicated power, red ones to indicate hard drive access and other colors to indicate standby, floppy access, or diagnostic activity. LEDs generally produce a single wavelength of light as low-voltage electrical current flows through the device. The colors of light available from different LEDs encompass the entire visible spectrum and even lightwaves that reach into the infrared and ultraviolet wavelengths. By combining more than one color of LED device into a single package, you can have LEDs that produce different colors depending on the direction of the current. These are commonly used as system power indicator LEDs, since they can be green when on, yellow in standby mode and red in hibernation mode. LEDs are also used to show system diagnostics, power, and system standby status. One purpose of these LEDs mounted on your system board is to remind you that just because the system is "off", it does not mean that it does not have power! Along the lines of the system diagnostic LEDs, is memory with built-in status indicators - Corsair makes memory modules that constantly display memory access and activity while the computer is running.