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From: mcginnis@kuhub.cc.ukans.edu
Newsgroups: sci.electronics
Subject: Re: 80386.
Message-ID: <27675.27820e85@kuhub.cc.ukans.edu>
Date: 2 Jan 91 22:47:01 GMT
References: <1990Dec18.234020.2491@uoft02.utoledo.edu> <1990Dec28.210731.10685@zoo.toronto.edu>
Organization: University of Kansas Academic Computing Services
Lines: 29

>My friend told me that we can use 16Mhz 80386 DX CPU on 25Mhz 80386 DX
>motherboard.
>Is it reliable?  Will it destroyed chips on the motherboard?


Go ahead and try.  It is unlikely to cause any hardware damage.

The way Intel determines chip speeds is at the "back end" of production,
after the chip has been packaged.  The packaged chips are tested under
a variety of conditions and speeds.  If the chips fail at a high speed
they are tested at consecutively lower speeds.  There is no manufacturing
difference between fast and slow chips.

Intel does rather tough testing so it is quite possible that a chip 
that could not pass _their_ testing at 25 MHz would perform adequately
when installed in a PC.  But it might not.

Consider that the damage done by a malfuctioning microprocessor
depends partially upon what the processor is doing when it screws
up... was it updating an important file?  Does it address the
wrong I/O address?  Does it hang?

Lots of things can be run OK beyond their specifications.  EPROMs and
RAM chips often work OK at higher speeds.  You can often format a
20 MB hard disk as a 40 MB and still have relatively few bad
sectors.

It's your machine and your data.  If you want to play Russian Roulette
then good luck.