"Syncing cpus" on a multi-cpu, dual core system

[soralx at cydem.org]

> On a computational chemistry list I subscribe to there is a
> current thread about multi-cpu systems needing to have the cpu
> frequencies synced (this is in a Linux context).  This is
> evidently not just having the cpus running at nominally the same
> frequency but something else in addition.  A posting in the thread
> said variations less than 0.1% were not problematic.  However, the
> poster said it was an issue in a dual cpu, dual core system he had
> set up.
> 
> My questions are:
> 1. Is this real or an urban legend?

If CPUs use the same FSB (as is the case with dual-core chip), they are
already in sync. Right? For system that use multiple FSB clocks [like
dual-(dualcore-CPU) systems], it might be possible to vary the clocks
(as much as the manufacturer allows without hw modifications: e.g.,
SpeedStep, or something similar).

Why someone would want to have CPUs running at precisely the same
frequency is beyond my imagination.

> Bud Dodson

[SorAlx]  ridin' VN1500-B2