Date: Wed, 7 Apr 1999 11:46:02 +0930 From: Greg Lehey <grog@lemis.com> To: Mark Ovens <marko@uk.radan.com>, Darren Pilgrim <dpilgrim@uswest.net> Cc: "Dragon Knight ][" <dragonknight@dtgnet.com>, FreeBSD Questions <questions@FreeBSD.ORG> Subject: Re: K6-2/333, was: Re: Debug kernel by default (was: System sizewith -g) Message-ID: <19990407114602.Z2142@lemis.com> In-Reply-To: <19990407025433.C4453@marder-1.localhost>; from Mark Ovens on Wed, Apr 07, 1999 at 02:54:33AM %2B0100 References: <Pine.LNX.4.04.9904051605450.10244-100000@hades.riverstyx.net> <3709569A.70EEC38A@uswest.net> <37097B00.2186EB92@dtgnet.com> <3709EDEB.BE17A2E8@uswest.net> <19990407025433.C4453@marder-1.localhost>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wednesday, 7 April 1999 at 2:54:33 +0100, Mark Ovens wrote: > On Tue, Apr 06, 1999 at 04:20:11AM -0700, Darren Pilgrim wrote: >> "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. > > As the person who effectively started all this discussion about > bus speeds and multipliers I just want to thank all the contributors > to this thread. I now have a better understanding of how it all > works. The fundamental misunderstanding I had was that the CPU > itself did the mutliplication and that the m/b jumpers simply "told" > the CPU what multiple of the bus speed to use. It does. But there are various parts of the CPU. The part which creates the CPU internal clock is just a bit of relatively simple hardwired logic. > I guess that AMD only state 95MHz & 3.5X, and not 66MHz & 5X, > because it gives the maximum absolute performance of the chip as > the CPU <==> memory is running at its highest speed. Correct. And in fact I'd guess that you could probably choose 100 MHz. I've been running this chip for over a week now, and it seems to be fine, so I suppose it's time to start experimenting with overclocking. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19990407114602.Z2142>