An energy-saving PC. All modern computers, printers and monitors are greener than their predecessors. After a certain period of time, they switch into low-voltage modes or turn off, although these settings are often user definable. Laser printers especially waste a lot of energy when not in use, because of their heat-induced fusing mechanism.
Contemporary CPUs often run at variable clock rates and can idle at lower speeds to save electricity. When required, they ramp up to full power. See green
The Green Ghost
Years back, this device was used to turn older laser printers off after a specified period of inactivity. As soon as the data reached the print spooler, the printer turned on and warmed up. (Image courtesy of Intelligent Computer Solutions.)