Hello David,

  DL> Actually you want the second generation, they have a
    > much lower power output than the early ones. The early
    > ones ran a 25MHz bus clock, the later 33MHz, IIRC a
    > P100 could be either sort.

Avoid 60 and 66MHz (Socket 4) Pentium chips because they're
5V, run hot and potentially contain the infamous FDIV bug.
As I understand it all Socket 5 and some Socket 7 boards are
3.5V.  Other Socket 7 support split core and i/o Voltages:
commonly 2.8V core, 3.3V i/o.

My understanding of Pentium bus frequency/multiplier/
processor speed relationship is...

  Pentium
              x1 x1.5    x2  x2.5    x3
    50 MHz         75
    60 MHz    60   90   120   150   180?
    66 MHz    66  100   133   166   200

  Pentium MMX
              x1 x1.5    x2  x2.5    x3  x3.5
    66 MHz                    166   200   233

       ...in any case, I probably wouldn't opt for a vintage
Pentium machine unless I happened to have one laying around.

I have to build at least one firewall machine soon.  I need
something that's going to be cool (preferably because it
doesn't generate stupid amounts of heat in the first place)
and reliable (the fewer moving parts, the better).  It will
live in a basement, so noise isn't an issue.

I'm looking at a system built around VIA's EPIA 5000 "Eden"
mainboard.  The 533 MHz microprocessor is plenty fast enough
for what I have in mind, and I don't have to worry about the
processor fan seizing because the chip doesn't need one.
Some of the available mITX cases have an external power
supply that's also fanless.

A site I've found useful is http://www.mini-itx.com/

  DL> A 60MHz or 100MHz sparc cpu will run fanless, probably
    > even without a heatsink.

I'm keeping my SPARCstation for use at home. ;-)

  - Andy Ball.