# SSC Jumper Mode?



## shajbot

I've seen several SATA WD hard drive have this kind of jumper mode (1-2), so what is SSC and is there any different if it's enable or not?


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## ENTERPRISE

Spread spectrum is the Protocol in which EMI is reduced. EMI is Electro Magnetic Interference . Having SSC enabled will impact on your performance and i would reccomend you have it disabled if you can.


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## PiratesRule

Heh, I just got done reading an explanation of this in Maximum PC in the ask the doctor section in August 2006. Heres a summary.

Quote:

SSC spread-sprectrum clocking lowers peak spectral energy-thus EMI by modulating the frequency of the clock signal by a small amount, usually .1-.5 percent.

During a third party lab testing they said that EMI emissions didnt really vary with it on or off. it affected performance with it on becuase the intentional modulation of the clock frequency-however minor-eats away at the drives valuable jitter-tolerance margin.


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## ENTERPRISE

Yes nice find..thats pretty much what SSC will do when enabled even though the performance decrease is small we want all the performance we can get so i would disable it.


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## shajbot

OK, thanks ENTERPRISE1701 and PirateRule.

Does this also apply to AGP graphic card? I see an option in BIOS say enable spread spectrum, so I would disable it to get better perf?


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## PiratesRule

Quote:


Originally Posted by *shajbot*
OK, thanks ENTERPRISE1701 and PirateRule.

Does this also apply to AGP graphic card? I see an option in BIOS say enable spread spectrum, so I would disable it to get better perf?

Yeah it should be disabled if youre overclocking.


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## ENTERPRISE

Quote:


Originally Posted by *shajbot*
OK, thanks ENTERPRISE1701 and PirateRule.

Does this also apply to AGP graphic card? I see an option in BIOS say enable spread spectrum, so I would disable it to get better perf?

Yes if there is an option to disable it i would do so.


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