Question Does spread spectrum clocking degrade a CPU's performance and cause it to operate at higher temperatures?

[Geremia]

Does spread spectrum clocking cause a CPU to operate at higher temperatures? If so, why?

Spread spectrum clocking minutely varies a CPU's clock speed to spread out RFI to meet FCC and EU guidelines.

I disabled spread spectrum in my BIOS, and my CPU is running ~20°C cooler!

I also noticed that disabling spread spectrum sped up my computer. According to luminaris here, "enabling spread sprectrum actually hurts performance". Why is this?

 

[CountMike]

You probably noticed that BCLK never stays at 100 but mostly fluctuates few 0.x bellow. That's spread spectrum at work adjusting BCLK to match memory, PCIe etc, everything that depends on it. Adjusting BCLK and SS can make it run at set frequency so if at or above 100 it may help performance but under 100 can hurt it.

 

[drea.drechsler]

... According to luminaris here, "enabling spread sprectrum actually hurts performance". Why is this?

I believe the 'theory' is that the bouncing around of the bus clock (as SS does) makes the processor clock speed and all other system clocks fluctuate right along with it and that can leave the system a little bit unstable in a heavily overclocked scenario.

That instability means you'll settle in on a lower overclock than you could with a SS disabled thereby degrading performance.

I personally believe if you're so close to the stability line that SS makes the difference you're doing it wrong.