The Athlon Powersaving HOWTO describes a way to make your Athlon, Duron or Athlon XP microprocessor consume less power when it's unused, i.e., when the null process of the operating system is executed. This process does nothing; it's just an endless loop, activated when no other process can use the CPU. So why use the entire power of the microprocessor when the null process is running?
To make these microprocessors consume less power, they need to be disconnected from the FSB, a process that can be done with just two commands. This is what the HOWTO explains. It also covers some common problems that may appear after doing this, as well as workarounds for them.
I just tried it and the processor reduced its temperature around 10�C! Yeah, I know, make system load go up and it will return to its normal temperature. But many CPUs are not overloaded all the time, so this little trick can increase their life significantly.
It's a pity it only works in Linux. I guess I'll have to port it to NetBSD... I mean... try to ;)