Are PCI Bus and Memory Bus speed always linked??

invasivedoc

Member
Nov 10, 2000
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The writeups on the KT-133A/KT-266 mobos got me thinking. The processors and memory can be oc'ed to 150+MHz easily, however peripherals are happiest when the PCI bus runs at its poky 33 MHz. For example I have a Pinnacle DC10+ that has the reputation of getting indigestion from plain-jane AMD units.

Q: Will the new mobos allow FSB/Memory bus OC while keeping PCI bus speed near 33 MHz. If not, why not?

Thanks.
 

dougjnn

Senior member
Dec 31, 2000
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To amply what has already been said --

The pci bus runs as a multiple of the fsb. The multiple can be changed, but only in large jumps. There are different "dividers" that come in at 66, 100 and 133 fsb, to get the PCI equal to 33. When you up the fsb from one of these three design speeds to get a bit more ooomph, you ALWAYS end up running your PCI faster than 33.

Of course the main way of overclocking Tbirds is by changing the multiplier, not the fsb. Then some people also try to get a bit more gain by also upping the fsb a bit with tbirds.

(It is the Intels which can only overclock through increasing the fsb.)
 

invasivedoc

Member
Nov 10, 2000
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Ok....Lets say you OC to 150 MHz. What would you adjust the divider to and what would PCI bus speed be? Do all your 'premium' boards have this adjustment?

Thanks.