FVCool is the FreeBSD version of the famous VCool software
(http://vcool.occludo.net) which changes the PCI configuration data
of some chipsets and thus allows AMD Athlon/Duron CPUs to go into
power-save mode. This makes the CPU consume a lot less electric
energy, and it produces a lot less heat as well. This trick is not
a secret - on FreeBSD, you can actually achieve the same effect
which this software has using the "pciconf" command.

Please note that this software may have a negative impact on the
system's stability and thus should not be employed in production
or mission-critical environments.