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Why drop the Multi

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a b à CPUs
a b K Overclocking
April 20, 2009 9:57:12 PM

Look i know this is bound to be one of those questions that gets asked time and time again. But...

Could someone please be so kind as to tell me why when overclocking i would want to run a higher FSB with a lower Multi.
I will probably see the light once told but cant for the life of me see why at the minuite.

Thanks

Mactronix

More about : drop multi

a b à CPUs
a b K Overclocking
April 20, 2009 10:01:31 PM

It depends, really - A given CPU may not like to be run that hard, while a motherboard might still have some headroom. A higher FSB clock gives slightly better/faster memory throughput. Also, some combinations may run better than others. Hell, sometimes, individuals may simply like round numbers <whistles innocently>.

But at the end of the day, a processor running at the same clock speed via one or another combination of FSB/Multi is going to perform the same.
April 20, 2009 10:05:36 PM

Only reason would be to be able to run a higher fsb and to run your ram at 1:1.
For example let say the max stable oc for your chip is 3.6Ghz and the multiplier is 10x. This means your fsb is 1440 and you ram is 720Mhz when 1:1.
If you drop the multiplier to 9x, then you can run 1600fsb, and 800mhz ram speed while at 3.6ghz. This will result is a small performance gain.
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a b à CPUs
a b K Overclocking
April 20, 2009 10:21:59 PM

So in real world terms its not something i should worry about then ? I get that a faster FSB can shift more data but couldnt see how that would help considering you were dropping the multi. I guess there is a sweet spot where it would help but from your replies it seems its not really worth the effort.
One more question if i may. If i do decide to test this out will running a faster FSB with a lower multi result in more heat ?
I just started OCing my 4600 and am at 2.77 so though i would stop and run it a while and get some answers to this.

Thanks a lot guys

Mactronix
April 20, 2009 10:29:24 PM

Not all cpus are able to run a high fsb. So, having a higher multiplier lets you oc more with a lower fsb. A higher fsb can add a little more heat to the cpu. And it will put more strain and heat to the northbridge. If you're just starting out overclocking the chip, then leave the multiplier at it's highest. Once you find the max stable overclock, then you can try tweaking.
April 21, 2009 4:35:14 AM

Well I thought it was that everything communicates through the Front Side Bus. All components. So lowering the multiplier would allow you to raise the FSB which would let everything else communicate more quickly, even if the cpu is running at the same speed.
a c 172 à CPUs
a c 197 K Overclocking
April 21, 2009 1:17:28 PM

yadge said:
Well I thought it was that everything communicates through the Front Side Bus. All components. So lowering the multiplier would allow you to raise the FSB which would let everything else communicate more quickly, even if the cpu is running at the same speed.

Not all components are tied directly to the FSB. But otherwise, theoretically, yes. In practice, you would need a good benchmark program to tell the difference.
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