The impact of clock spread spectrum in BIOS on sound

[here7423]

Spread Spectrum technology is a commonly used wireless communication technology, referred to as spread spectrum technology. When the clock generator on the motherboard is working, the peak of the pulse will generate electromagnetic interference (EMI). Spread spectrum technology can reduce the electromagnetic interference generated by the pulse generator.

For my M13A motherboard, enter the BIOS and search for spread spectrum, and you can see 3 spread spectrum items:

Power module: VRM spread spectrum
CPU clock: BCLK spread spectrum
PCIe channel: PCIE spread spectrum

First, it is clear that the role of spread spectrum is to prevent external interference, rather than to protect and shield external interference from inside
If the computer is used for overclocking, these 3 spread spectrum items may need to be turned off
But if the computer is used for audio, theoretically only turning off this spread spectrum on the PCIe signal channel will reduce the negative impact of the spread spectrum.

Interested friends can compare the difference between turning on and off each spread spectrum in the BIOS.

 

[Lohil]

Spread Spectrum technology is a commonly used wireless communication technology, referred to as spread spectrum technology. When the clock generator on the motherboard is working, the peak of the pulse will generate electromagnetic interference (EMI). Spread spectrum technology can reduce the electromagnetic interference generated by the pulse generator.

For my M13A motherboard, enter the BIOS and search for spread spectrum, and you can see 3 spread spectrum items:

Power module: VRM spread spectrum
CPU clock: BCLK spread spectrum
PCIe channel: PCIE spread spectrum

First, it is clear that the role of spread spectrum is to prevent external interference, rather than to protect and shield external interference from inside
If the computer is used for overclocking, these 3 spread spectrum items may need to be turned off
But if the computer is used for audio, theoretically only turning off this spread spectrum on the PCIe signal channel will reduce the negative impact of the spread spectrum.

Interested friends can compare the difference between turning on and off each spread spectrum in the BIOS.

I'm a professional computer engineer and tbh I've not heard of spread spectrum on my clocks
But certainly is creative tech, and looking into it, it becomes a bit rabbit hole as to what it actually does from an EMI standpoint, with some saying it pragmatically does nothing.

In terms of overclocking you'd turn it off because you are going to cause some jitter, which despite the best efforts of w/e they use to take out the SSC (PPLs, TIEs, VCOs etc.) eventually as you push to the limit of what your hardware can do, you fail some critical timing.

As for if this will effect audio, well it could do it in two ways the same jitter that effects the OC timings could be introducing jitter on your DAC's clock, or the theoretically the SSC freqency itself could show up on the analoge side of things.

In terms of the effect of digital jitter my guess is that it's all taken out by some PLL and the effect of jitter on your sample rate wouldn't be noticable.
On the analogue side of things while it is possible it could show up, it looks like the standards put the modulation at 30-33KHz triangle which was done in part with the intent it not interfere with audio components (or at least what would be audible).

Both very measurable though, it would be intresting to take a oscope to the line out and see if you can see a ~30KHz noise on a spectral plot of the DAC output, with and w/o SSC turned on. Measuring the clock jitter on the DAC would be a little bit more tricky but you could probe the DACs clk and take a jitter measurment.

 

[Roseval]

Measuring the clock jitter on the DAC would be a little bit more tricky but you could probe the DACs clk and take a jitter measurment.

I suggest to run to run a J-test so using the analog out of the DAC. That is what we are going to hear.

 

[sygnus21]

Spread Spectrum technology is a commonly used wireless communication technology, referred to as spread spectrum technology. When the clock generator on the motherboard is working, the peak of the pulse will generate electromagnetic interference (EMI). Spread spectrum technology can reduce the electromagnetic interference generated by the pulse generator.

For my M13A motherboard, enter the BIOS and search for spread spectrum, and you can see 3 spread spectrum items:

Power module: VRM spread spectrum
CPU clock: BCLK spread spectrum
PCIe channel: PCIE spread spectrum

First, it is clear that the role of spread spectrum is to prevent external interference, rather than to protect and shield external interference from inside
If the computer is used for overclocking, these 3 spread spectrum items may need to be turned off
But if the computer is used for audio, theoretically only turning off this spread spectrum on the PCIe signal channel will reduce the negative impact of the spread spectrum.

Interested friends can compare the difference between turning on and off each spread spectrum in the BIOS.

I think some are deep diving into areas of zero to very little if any impact on audio improvement here. You'd get far better results in switching cables or upgrading gear than having "Spread Spectrum being an issue. And certainly nothing you're ever going to hear.

I run two DACs off my PC, and I've never tweaked any BIOS "strictly for audio" reasons. And I've only been building PCs since 1998, with my last build in 2019, and a new one coming in 2025. And yes, building also means configuring a BIOS

 

[kingoftown1]

FWIW previously owning a Hypsos got me thinking about this. The Hypsos sounded better to me with its spread spectrum turned off. I've done a decent amount of tweaking to my server, and currently have spread spectrum (BCLK) turned off. However, I made a few other changes at the same time, and haven't taken the time to A-B them individually yet.

I'd recommend this guide as a good starting point for OS & Bios tweaking.

 

[sygnus21]

I'd recommend this guide as a good starting point for OS & Bios tweaking.

It would be helpful and safer if you alerted members your link results in your PC trying to download a file!!!

I myself do not download from members or sites I do not know as a matter of safety.

 

[kingoftown1]

Well, alternately, you could search for "Guide for Optimizing WS2019 in a Dual or Single PC JPLAY Femto-Based System" -- but it's really more geared for purpose-built audio pcs, not general purpose computers that just happened to have a dac connected.

 

[sygnus21]

Well, alternately, you could search for "Guide for Optimizing WS2019 in a Dual or Single PC JPLAY Femto-Based System" -- but it's really more geared for purpose-built audio pcs, not general purpose computers that just happened to have a dac connected.

Sure, champ anything you say. I'll let others take their chance on your poison pill.

Good luck.

 

[here7423]

I think some are deep diving into areas of zero to very little if any impact on audio improvement here. You'd get far better results in switching cables or upgrading gear than having "Spread Spectrum being an issue. And certainly nothing you're ever going to hear.

I run two DACs off my PC, and I've never tweaked any BIOS "strictly for audio" reasons. And I've only been building PCs since 1998, with my last build in 2019, and a new one coming in 2025. And yes, building also means configuring a BIOS

There are many links in the computer. If you tinker with these accessories, it will only make the system sound biased, resulting in a local strong biased sound system, and the sound is unbalanced. I also listened to the BIOS in the default setting state for a long time, but the sound source we used was undoubtedly a PC built for gaming. There are similarities and differences with audio-specific PCs. Unfortunately, these motherboard manufacturers did not provide an option mode in the BIOS for audiophiles to choose.

 

[kingoftown1]

@sygnus21 not sure where all the hostility's coming from. I use a number of the tweaks in that guide in my stereo system, which has a dedicated audio pc. On the other hand, my headphone setup is more general purpose/productivity/gaming and it wouldn't make sense to use this guide given the use case. From what I recall, your head-fi setup is similar in that sense. Nothing wrong with that.

On the flip side, there are others out there with dedicated machines & the requisite knowledge-base to not screw their computer up. Once you get to a certain point where "the next upgrade" tends to be more than you'd want to spend, it would make sense to take a look at what optimizations & system improvements you can implement where the only cost is your time.

 

[here7423]

Most of the changes recommended in some BIOS setup guides do not come with instructions on how the listening experience will change. You need to use your own ears to rationally test and verify each option. The truth needs to be tested with your ears. However, personal listening is indeed very personal, and those sounds will also be affected by the deviation corrected by the post-amplification. In this topic, there are 3 spread spectrum items. Only the spread spectrum of PCIE/DMI is turned off, the EMI from the power supply and CPU is turned off, and the original state of the data channel PCIE/DMI is maintained. It is logical. Compared with before adjustment, my personal listening experience (reference) is that the high and low frequencies are better extended, the mid-frequency is no longer so prominent, and the music details become more fascinating, but it seems that the overall strength seems to be somewhat weakened. I really want to know what settings and listening experiences you have made in your BIOS besides the default faction.

 

[Lohil]

Most of the changes recommended in some BIOS setup guides do not come with instructions on how the listening experience will change. You need to use your own ears to rationally test and verify each option. The truth needs to be tested with your ears. However, personal listening is indeed very personal, and those sounds will also be affected by the deviation corrected by the post-amplification. In this topic, there are 3 spread spectrum items. Only the spread spectrum of PCIE/DMI is turned off, the EMI from the power supply and CPU is turned off, and the original state of the data channel PCIE/DMI is maintained. It is logical. Compared with before adjustment, my personal listening experience (reference) is that the high and low frequencies are better extended, the mid-frequency is no longer so prominent, and the music details become more fascinating, but it seems that the overall strength seems to be somewhat weakened. I really want to know what settings and listening experiences you have made in your BIOS besides the default faction.

Mmm I'm not sure trying to listen for it is warranted yet, I guess you need access to the equipment but I'd first confirm there's an effect to the signal at all on a high-speed scope before attempting to see if one actually hear it.

 

[here7423]

Disabling C-STATES will make the far field of sound become near field, the sound pressure of the speaker will be enhanced, Compared with the sound under full default settings, the outline of the sound has not changed. With the setting of disabling PCIE/DMI spread spectrum, the mid-frequency becomes less prominent, and the chord part of the drum and bass strengthens the sense of music. Before finding other settings that can significantly improve SQ, only adjust these two items, keep the others at the default settings.

 

[Pictus]

FWIW previously owning a Hypsos got me thinking about this. The Hypsos sounded better to me with its spread spectrum turned off. I've done a decent amount of tweaking to my server, and currently have spread spectrum (BCLK) turned off. However, I made a few other changes at the same time, and haven't taken the time to A-B them individually yet.

I'd recommend this guide as a good starting point for OS & Bios tweaking.

My guide https://www.kvraudio.com/forum/viewtopic.php?p=8820694#p8820694
I use all, but keep MPO(Multi-plane overlay) enabled.

 

[here7423]

Now it is different from the past. Since the system disk is in the PCIE channel, any setting that can improve the PCIE performance will make the sound quality change noticeably.

Taking the sound of the BIOS full default settings as a reference, we disabled "C state" and "PCIE/DMI spread spectrum", and the sound became much more stretched and pleasant.

On this basis, today I set the "PCIe speed" option from auto to Gen 3, set it to the highest, which allows the computer to run at high performance even under low load, and the sound becomes denser and thicker, with a gushing momentum. Another "AVX Offset" is set to 0 to prevent the CPU from downclocking when running other programs.

So far, it is clear that these 4 changes have been verified by my eardrums to be completely correct. I am curious about what other mysterious settings in the BIOS can improve the sound quality.