Linux-Ecology-HOWTO

Miscellaneous Power Saving Techniques

Linux halts the CPU in the idle cycle to further reduce power consumption. Early reports of OS/2, Win3.1/95, NT, and Linux showed Linux to use far less power than DOS-based O/S's that spun in the idle loop and consumed power -- this may have changed hence it would need research to validate.

Most Linux-users tend to leave their computer on for years whenever possible. However, several modern BIOS's support an unattended powerup, and with cron you can even do an unattended shutdown. No need to leave the computer on night after night. Other techniques to powerup your computer at certain times are: ACPI-Wakeup, NVRAM-wakeup and the settime command. Computers can even be power up on request remotely by means of Wake-on-LAN using a network connection or Wake-on-Ring using an old fashioned serial interface and a modem.

Beware of animated web pages! Web pages containing Flash, Java, or just animated images can consume a lot of CPU. When you leave your computer and keep it on, make sure you close all browser pages with animations. Otherwise, your PC may be left running at full speed while you are not using it.

To disable animated images in Mozilla Firefox go to about:config, find image.animation_mode and change its value to none or once.

Do not forget to switch off your DSL modem / wireless router / ISP box / printers at night or during vacations if you don't use them. These devices consume quite a lot (typically 15W).