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Date:      Tue, 06 Apr 1999 04:20:11 -0700
From:      Darren Pilgrim <dpilgrim@uswest.net>
To:        "Dragon Knight ][" <dragonknight@dtgnet.com>
Cc:        FreeBSD Questions <questions@FreeBSD.ORG>
Subject:   Re: K6-2/333, was: Re: Debug kernel by default (was: System sizewith -g)
Message-ID:  <3709EDEB.BE17A2E8@uswest.net>
References:  <Pine.LNX.4.04.9904051605450.10244-100000@hades.riverstyx.net> <3709569A.70EEC38A@uswest.net> <37097B00.2186EB92@dtgnet.com>

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"Dragon Knight ][" wrote:
> Darren Pilgrim wrote:
<snip>
> > While this is mathematically and theoretically sound thinking, tests
> > have shown that there is little CPU/memory performance gain with a
> > 100MHz bus.  Just take a look at www.tomshardware.com.  As for my own
> > systems, I run K6-2 333s at 5x66 just because it sets the PCI and AGP
> > clocks at their spec'd rate of 33 and 66MHz, respectively, while
> > providing the CPU's spec'd 333MHz.
> >
> 
> As you say, there is a little CPU/Memory performance increase at 100MHz fsb.
> So I do not see your logic in setting your chips at 5x66 because it puts your
> PCI and AGP where they should be.  One of the 'specs' of the 100MHz fsb is
> that PCI and AGP cards will run at their normal speed of 33 and 66MH.  I believe
> this is also true of the 95MHz busses.

Actually I said "there is little", I didn't put an "a" in there.  Plus
the only performance increases I've ever seen are on stress-test
benchmarks where the disk, memory, and video are all in use at once.
This situation is purely for performance testing, there's is no real-
world application.

95MHz produces slower AGP/PCI clocks and, lacking a performance gain
with a faster FSB, using 66MHz to get faster AGP/PCI clocks makes more
sense if your CPU isn't rated for a 100MHz multiple.  This is just
splitting hairs; IRL, a <4MHz clock difference is nothing performance
wise.  Your cards might complain about it though.  Particularly the
ones that rely on the bus-clock for their internal clocks, like some
sound and video cards.

-- 
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