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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!newshost.telstra.net!act.news.telstra.net!psgrain!usenet.eel.ufl.edu!gatech!newsfeed.internetmci.com!howland.reston.ans.net!ix.netcom.com!netnews From: cprohman@ix.netcom.com (Carl Rohman) 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? Date: Mon, 04 Mar 1996 04:49:35 GMT Organization: Netcom Lines: 42 Message-ID: <4hdspu$hn@cloner3.netcom.com> References: <DnpJqF.82n@info.elvisti.kiev.ua> NNTP-Posting-Host: ix-lin-ne1-04.ix.netcom.com X-NETCOM-Date: Sun Mar 03 8:50:06 PM PST 1996 X-Newsreader: Forte Free Agent 1.0.82 Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:14819 alt.comp.periphs.mainboard.asus:11863 comp.sys.ibm.pc.hardware.systems:28430 comp.os.linux.hardware:32107 comp.sys.intel:66398 stesin@elvisti.kiev.ua (Andrew V. Stesin) 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.)? >I always thought that PCI will than run at 40MHz too. >But was told today that it will be only 20MHz?! Oh God. >How can I check this for sure, without running hated benchmarks, >but only by exploration of MB jumpers? >I was also told that having 40MHz will probably cause >an addition of extra wait states for cache and RAM access, >thus making a box considerably _slower_ for real work >than with 33MHz CPU main frequency, especially for UNIX-like OS >(FreeBSD in my case, but who cares). Any comments on this one? >And, in case both statements are true, why bother looking >at (X * 40)MHz 486 CPUs at all? My GA5486AL with Cyrix 120 (3x40) runs faster at 3x33 due to extra wait states in accessing cache and ram. If the board will take 12ns SRAM, this should allow the cache to keep up. >Thanks for your comments! >P.S. I don't own a PCI box, but just planning to buy one, choosing > the best bang-per-buck configuration now. > Was considering AMD 160MHz (glorified 486, called 5x86, he-he :) > chip, which has 40MHz main freq and 4x multiplier. > Now I'm seriously considering AMD 133 part (this one is 33MHz, 4x). > Guys have a very nice opinions on it. >-- > With best regards -- Andrew Stesin. > +380 (44) 2760188 +380 (44) 2713457 +380 (44) 2713560 > "You may delegate authority, but not responsibility." > Frank's Management Rule #1.