"Power management on computers has three parts: selecting
devices that are more power-efficient, tuning your systems to run
more efficiently, and configuring systems to use less power during
periods of inactivity. Servers, desktop machines, and laptops
usually need different power management schemes; there isn't a
one-size-fits-all. The first step is finding the power hogs on your
systems, so today we'll learn how to measure hardware power usage.
We'll also expose and rein in power-hog processes, and next week
we'll learn some ways to get the most bang per watt on our Linux
"The first lesson in power management on modern electronics is
understanding that nothing is really off until you pull the plug.
In my own personal computer lab I acquire a nice tan with the
computers and room lights turned off. Routers, printers, surge
protectors, backup power, speakers, and monitors all emit a
radiant, friendly glow from their many LEDs. I have a running peeve
with Hewlett-Packard over power switches on printers. My old HP6L
doesn't even have a power switch. The newer Laserjet 3050 has a
switch located on the back, way down at the bottom, requiring a
long double-jointed arm to reach it. I'm waiting for HP to claim
green creds so I can scoff at them..."