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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!spool.mu.edu!daily-planet.execpc.com!news.sol.net!news.inc.net!trellis.wwnet.com!nntp.coast.net!howland.reston.ans.net!math.ohio-state.edu!jussieu.fr!citi2.fr!aemiaif.math-info.univ-paris5.fr!tarreau From: tarreau@aemiaif.math-info.univ-paris5.fr (Willy TARREAU) Newsgroups: comp.unix.bsd.freebsd.misc,alt.comp.periphs.mainboard.asus,comp.sys.ibm.pc.hardware.systems,comp.os.linux.hardware,comp.sys.intel Subject: Re: PCI bus freq with CPU freq at (X * 40)Mhz? Followup-To: comp.unix.bsd.freebsd.misc,alt.comp.periphs.mainboard.asus,comp.sys.ibm.pc.hardware.systems,comp.os.linux.hardware,comp.sys.intel Date: 13 Mar 1996 10:12:42 GMT Organization: CITI2 - Universite Rene Descartes, Paris Lines: 41 Message-ID: <4i672q$8vh@bisance.citi2.fr> References: <DnpJqF.82n@info.elvisti.kiev.ua> <4hg8sa$1jn@heist.demon.co.uk> <Dns7BK.DBI@ritz.mordor.com> <slrn4jolrv.3na.louis@lcjones.aclib.siue.edu> NNTP-Posting-Host: aemiaif.math-info.univ-paris5.fr X-Newsreader: TIN [version 1.2 PL2] Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:15558 alt.comp.periphs.mainboard.asus:12739 comp.sys.ibm.pc.hardware.systems:29280 comp.os.linux.hardware:33492 comp.sys.intel:67869 Louis J. LaBash Jr. (louis@LCJones.aclib.siue.edu) wrote: : On Tue, 5 Mar 1996 06:28:32 GMT, Chris Mauritz <ritz@ritz.mordor.com> wrote: : |Iain Baird (iain@heist.demon.co.uk) wrote: : |: Andrew V. Stesin (stesin@elvisti.kiev.ua) wrote: : |: : Sorry for ignorance, but what will be the frequency on a PC's PCI bus : |: : when the CPU runs at main frequency of 40MHz (DX2/80, DX4/120 i.e.)? : [deleted] : : |: Having said that, I have run PCI at 40MHz with a DX4-120, and it : |: worked (with AHA-2940 and S3-968). This made little or no difference : |: to kernel build times compared to 20MHz, although this is a crude : |: benchmark. Doing this could reduce the life expectancy of PCI : |: cards. : | : |Reduce the life expectancy? How? My experience has been that : |overclocked cpu's/cards either work or don't work from square : |one...they don't work and then fail. If you have different : |experience please share. I'd hate to think I'm risking expensive : |cpu's and #9 graphics cards... : Sure can, power-dissipation is proportional to speed, and power- : dissipation spells *heat*; that's why high-speed CPUs require heat- : sinks and fans. Look at some semiconductor data-sheets: you'll see : "ABSOLUTE MAXIMUM RATINGS", temperature, Power Dissipation, and : voltage. "Stresses above those listed under ABSOLUTE MAXIMUM : RATINGS my cause permanent device failure. Functionality at or : above these limits is not implied. Exposure to absolute maximum : ratings for extended periods may affect device reliability." : The above is an excerpt from an IC data-sheet, and is typical. I had an experience with an AMD DX2/80 3.3 Volt which ran about one year 120 Mhz under 5V ! I was surprised to discover that when I set it back to 80 Mhz under 3.3V, it sometimes hanged, so I had to set it back to 5V ! My conclusion was: The CPU finally accomodated itself to the higher voltage ! But I've never had problems with overclocked CPUs at the same voltage. Willy