Subject: Re: Timeline for i386 SMP
To: Brett Lymn <>
From: Bill Sommerfeld <>
List: tech-smp
Date: 05/29/2000 08:03:29
> Well, if anyone can point me at a reliable source for the PII
> overdrive chips that are drop-ins for the PPros then I may just have a
> matched pair of pros that I don't know what to do with.  The rumours I
> have heard is that it is SUPPOSEDLY best to match the stepping level
> of both processors in a SMP arrangement.

You can get better than rumor..

search for 
	multiprocessor stepping

You'll see the "specification updates" for different processors pop

the latest PPro spec update says:
    "Though Intel recommends using identical stepping of processor silicon
    in multiprocessor systems whenever possibvle (as this is the only
    configuraation which recieves full validation across all of Intel's
    testing), Intel supports mixing processor steppings, and does not
    actively prevent various steppings of the Pentium Pro processor from
    working together in MP systems.  However, since Intel cannot validate
    every possible combination of devices, each new stepping of a decice
    is fully validated only against the latest steppings of other
    processors and chipset components".

Or, without weasel words, "It should work but we haven't completely
tested it.  You're on your own..".

The Pentium III spec isn't quite as blunt.. freely translated, "Feel
free to mix and match processors of identical clock speed and cache
size", but intel's been cranking up the clock speeds so much lately
that there aren't that many different steppings at a given speed..

					- Bill