Spread Spectrum Modulated

[tontod]

I see this option in the bios of the IWILL KK266R. Should I enable it or not? Not sure what it does.

 

[GundamF91]

I have that option in Epox 8K7A. I asked that here, and someone replied it being about not interferring with your home phones, ie. DSS, digital Spread Spectrum 900Mhz, 2Ghz handsets. So I guess that doesn't have anything to do with actual system performance. Just a radiation thing.

 

[roc]

wow, kinda wierd.

 

[Green Man]

<< I have that option in Epox 8K7A. I asked that here, and someone replied it being about not interferring with your home phones, ie. DSS, digital Spread Spectrum 900Mhz, 2Ghz handsets. So I guess that doesn't have anything to do with actual system performance. Just a radiation thing >>



I'm not so sure about that. I think that enabling it will provide cleaner signal to the memory at the expense of performance. I recommend leaving it off, which should be the default.

 

[Peter]

'nuff guessing folks.

Spread Spectrum Clock Modulation is about lowering peaks in the electromagnetic emission spectrum of the computer.

Problem is, since most frequencies in an x86 PC are multiples of each other, the emission spectrum has a few huge peaks exactly at those frequencies.

By letting those frequencies oscillate around their intended point, those peaks are flattened out to plateaus. Total emission is no less, but the peaks are gone - and it's the peaks that all those FCC and EC and whereintheworldyouare's legislations are about.

Does it affect performance? Usually, no. The frequencies oscillate up and down around their usual speeds, so while the thing bobs around being slightly faster and slightly slower all the time, the resulting speed is what it were without SSM.

Only if the modulation is set to be extremely wide, one has to modulate down-only instead of centered as to not exceed specified CPU and PCI bus frequencies. But this is rarely seen, usual clock synthesizer chips modulate from .25 percent to .5 centered.

So enable it. It doesn't hurt, and sensitive other electronic stuff near your computer may be working better.

regards, Peter

 

[lenjack]

Enable if only if you need to reduce EMI interference. I'm informed that it will affect performance if you're near your overclocking limit.

 

[boran]

my old (look at my hardware specs in my siggie ..) motherboard has a standard spread spectrum down of 2.5 mhz ... I'll just leave it at that scince that was the standard and recommended setting ..