My firewall machine (aka heap of random circuit boards) has a 6x86
processor, and because I'm running it fanless, was keen to get it as
cool as possible (mind you, with an open case and a cardboard roll on top
acting as a chimney, it seemed happy enough).

So anyway, I found the set6x86 program. In case you know nothing about it,
it basically lets you read and set the contents of all the
machine-specific control registers. It can be used for various tweaks,
most of which either have very little effect, or aren't very interesting
for floppyfw (e.g. increasing the video bandwidth). But one is very
interesting: it makes the chip power down when it executes the HALT
instruction.

I attach my package which contains the binary, and a post script which
calls it to activate power-down-on-HALT.

-- 
http://www.mupsych.org/~rrt/ | aphorism, n.  a wise lie