🚀 go-pugleaf

In article <OTTO.90Dec31040234@tukki.jyu.fi> otto@tukki.jyu.fi (Otto J. Makela) writes about using a 16 MHz 80386DX in a 25 MHz circuit:

> Actually, if it boots, it'll probably be (reasonably) reliable.  The 80386
> is such a complicated beastie that if it's even slightly flaky, it'll
> probably crash immediately.

Maybe, maybe not.

> It'll probably run hotter 'en 'ell, though.

Not unless the 25 MHz chips run hotter 'en 'ell.
The 16 and 25 MHz rated parts have the same circuitry implemented in the
same (mostly) CMOS process, so the power dissipation of the two will be
nearly identical at the same clock speed.

The 16 MHz part is simply not guaranteed to run at 25 MHz.  It may never
have been tested for 25 MHz operation, or it may have failed 25 MHz test
but passed 16 MHz test.

Keep in mind the the manufacturers speed rating applies over the entire
specified operating temperature range.  If you cool the chip, it will
be capable of running faster (although since Intel doesn't put that in
the specifications, they won't guarantee it).

In general, I personally consider it to be very poor engineering practice
to push parts past the manufacturers specs just to save a few $$$.  I
trust a lot of data to my computer, and that's worth more to me than a
one time savings of less than $100.  I wouldn't knowingly buy any product
in which such things are done.



--
Eric L. Smith      Opinions expressed herein do not necessarily reflect those
esmith@apple.com   of my employer, friends, family, computer, or even me!  :-)