Info Get PBO to work? Finally?

[drea.drechsler]

For us Zen2 users, with AGESA 1004b BIOS's PBO has seemed pretty much broke. Over at overclock.net, apparently it's bugs have been deciphered. Somewhat.

With my settings:
PPT=300 (experiment up or down a LOT...like +/-100...and it doesn't matter)
TDC=150 (same here, but like +/-50)
EDC=10 for 8 cores (15 for 12 cores; 20-25 for 16 cores; 6 or more than 16 cores experiment using the established trendline as guidance)
PBO Scalar - 5X-10X (experiment; I'm at 10X)

C States disabled, CnQ enabled
VCore = -0.0125, LLC disabled or a 'flat' load line (experiment with this, up or down a bit, for your board and CPU)

With my 3700X I get CB r20 performance, both multi thread and single thread, that's almost identical to an all-core, fixed voltage overclock that I'm never really certain is 'safe'. With this, it's ALWAYS a 'safe voltage' because SenseMI picks it from the FIT tables. Never a doubt!

It can run Prime95 at 4.2Ghz, all cores, sustained. That's 600Mhz above the 3700X base clock, 3.6Ghz, a 33% 17% overclock. I do also have it under a 240mm AIO; good cooling is important to keep it from pulling clocks. Previously the best PBO would get it to was 3.9Ghz. Really a very nice improvement!

EDITED: fixed bad math

 

[CountMike]

For us Zen2 users, with AGESA 1004b BIOS's PBO has seemed pretty much broke. Over at overclock.net, apparently it's bugs have been deciphered. Somewhat.

With my settings:
PPT=300 (experiment up or down a LOT...like +/-100...and it doesn't matter)
TDC=150 (same here, but like +/-50)
EDC=10 for 8 cores (15 for 12 cores; 20-25 for 16 cores; 6 or more than 16 cores experiment using the established trendline as guidance)
PBO Scalar - 5X-10X (experiment; I'm at 10X)

C States disabled, CnQ enabled
VCore = -0.0125, LLC disabled or a 'flat' load line (experiment with this, up or down a bit, for your board and CPU)

With my 3700X I get CB r20 performance, both multi thread and single thread, that's almost identical to an all-core, fixed voltage overclock that I'm never really certain is 'safe'. With this, it's ALWAYS a 'safe voltage' because SenseMI picks it from the FIT tables. Never a doubt!

It can run Prime95 at 4.2Ghz, all cores, sustained. That's 600Mhz above the 3700X base clock, 3.6Ghz, a 33% overclock. I do also have it under a 240mm AIO; good cooling is important to keep it from pulling clocks. Previously the best PBO would get it to was 3.9Ghz. Really a very nice improvement!

It's also a BIOS function but you didn't state MB or it's BIOS version.
My 3700x boosts up to 4.396MHz,0.05v negative offset with PBO at almost stock settings giving me CBr20 score average 5039/511. Max score was 5089/511
Max stable all core OC is only 4.3GHz though. with 1.37v giving CB r20 score 5244/511
For best PBO results it's necessary to keep max temps between 62 and 65c.
With all core OC temps over 75c are not a problem.

 

[drea.drechsler]

It's also a BIOS function but you didn't state MB or it's BIOS version.
My 3700x boosts up to 4.396MHz,0.05v negative offset with PBO at almost stock settings giving me CBr20 score average 5039/511. Max score was 5089/511
Max stable all core OC is only 4.3GHz though. with 1.37v giving CB r20 score 5244/511
For best PBO results it's necessary to keep max temps between 62 and 65c.
With all core OC temps over 75c are not a problem.

Yes, I forgot to mention these settings are being made in BIOS. I prefer that to RyzenMaster, in which I'm not even sure you can alter all the settings.

The CB20 scores I'm getting are 5150/511 with those PBO settings.

Although cooler temps always give best results it's very much relative as it varies depending on load, so I don't think it's as simple as saying temps under 65 are 'best'. For instance, when running Prime95 my temps hover right at 81C and I'm still getting 4.2Ghz (a 17% overclock). Fairly steady for hours on end with (STI2) core voltage hovering around 1.275V, picked by the CPU itself based on it's unique FIT data. Of course, running CB20 temps will be cooler, maybe in the mid-60's, with frequently much higher clocks on some cores.

BTW 1.375V FIXED is being discussed as unreliable and probably dangerous for 3700X'. I'd be very much afraid of putting my CPU under heavy loads, even just stress testing, with that fixed voltage for long. Examples are already popping up of overclockers degrading their CPU's.

The smart way to determine a "safe" fixed voltage is to basically ask your processor. Start with everything in AUTO, then put it under an extreme heavy/hot all core processing load like Prime95 (no AVX). Watch where voltage ends up as it lowers clocks and voltage to keep current and temperature in a safe range. Doing that, my processor drops down to hover around 1.27-1.28 Volts with a clock right at 3.6Ghz. With the PBO settings above voltage stays the same and temps the same but clocks around 4.2Ghz.

 

[CountMike]

Yes, I forgot to mention these settings are being made in BIOS. I prefer that to RyzenMaster, in which I'm not even sure you can alter all the settings.

The CB20 scores I'm getting are 5150/511 with those PBO settings.

Although cooler temps always give best results it's very much relative as it varies depending on load, so I don't think it's as simple as saying temps under 65 are 'best'. For instance, when running Prime95 my temps hover right at 81C and I'm still getting 4.2Ghz (a 17% overclock). Fairly steady for hours on end with voltage hovering around 1.275V, picked by the CPU itself based on it's unique FIT data. Of course, running CB20 temps will be cooler, maybe in the mid-60's, with frequently much higher clocks on some cores.

BTW 1.375V FIXED is being discussed as unreliable and probably dangerous for 3700X'. I'd be very much afraid of putting my CPU under heavy loads, even just stress testing, with that fixed voltage for long. Examples are already popping up of overclockers degrading their CPU's.

The smart way to determine a "safe" fixed voltage is to basically ask your processor. Start with everything in AUTO, then put it under an extreme heavy/hot all core processing load like Prime95 (no AVX). Watch where voltage ends up as it lowers clocks and voltage to keep temps safe. Doing that, my processor drops down to hover around 1.27-1.28 Volts with a clock right at 3.6Ghz. With the PBO settings above voltage stays the same and temps the same but clocks around 4.2Ghz.

And your MB is ?

 

[drea.drechsler]

And your MB is ?

B450M Mortar. Nothing spectacular.

But according to most posters, the PBO 'bug' is pretty much universal and it works very similar regardless of MoBo. The only criteria is that you're on a BIOS with AGESA 1004b, the latest/last AMD's released AFAIK.

 

[CountMike]

B450M Mortar. Nothing spectacular.

But according to most posters, the PBO 'bug' is pretty much universal and it works very similar regardless of MoBo. The only criteria is that you're on a BIOS with AGESA 1004b, the latest/last AMD's released AFAIK.

Yes but BIOS settings are not always same, with my latest BIOS settings for PBO are in two places with most settings being duplicated, voltage settings are also different than MSI's. Lots of things to juggle around, not easy to find right combo.

 

[drea.drechsler]

Yes but BIOS settings are not always same, with my latest BIOS settings for PBO ...

Yes! I know! and my MSI board with it's gimped BIOS (it's not a MAX B450 version) the settings in one area (under AMD Overclocking) aren't even complete. I'm using the settings in the Overclocking tab, which seems easier anyway as it's more logically arranged.

I did not try Ryzen Master to make the PBO settings, you could try that to see if how it works for you. You may have to go into BIOS to change the Advanced C States setting as well as the Cool n Quiet setting; those are important so it won't throttle in single thread. I'm pretty sure you also won't be able to change LLC settings in RM.

Be sure to set voltage to AUTO with zero offsets at first. You can try increasingly negative offsets as it helps keep temps lower in moderate loads, helping CBR20 MT scores in particular. Although too much can start impacting ST scores as too low a voltage won't let it boost high in light/bursty loads. Doing PBO this way seems to negate the clock-compression that occurs when negative offsets get too large.

 

[CountMike]

Yes! I know! and my MSI board with it's gimped BIOS (it's not a MAX B450 version) the settings in one area (under AMD Overclocking) aren't even complete. I'm using the settings in the Overclocking tab, which seems easier anyway as it's more logically arranged.

I did not try Ryzen Master to make the PBO settings, you could try that to see if how it works for you. You may have to go into BIOS to change the Advanced C States setting as well as the Cool n Quiet setting; those are important so it won't throttle in single thread. I'm pretty sure you also won't be able to change LLC settings in RM.

Be sure to set voltage to AUTO with zero offsets at first. You can try increasingly negative offsets as it helps keep temps lower in moderate loads, helping CBR20 MT scores in particular. Although too much can start impacting ST scores as too low a voltage won't let it boost high in light/bursty loads. Doing PBO this way seems to negate the clock-compression that occurs when negative offsets get too large.

I was experimenting with it ever since the beginning, first I had 2700x on this MB (earlier one was Asus Prime x370 pro. 1003abba AGESA was giving me higher frequencies under PBO but lower benchmarks. BIOS with 1003abba was 5220 and this one with 1004b is practically same save for AGESA. Hope Asus fixes it soon.

 

[drea.drechsler]

....
1003abba AGESA was giving me higher frequencies under PBO but lower benchmarks.
....

That's why I concentrate on BM scores instead of clock speeds. Mainly CineBench looking at both multi-thread and single thread scores. It's easy to kill single thread while making multi-thread look great. Single thread performance is critical for gaming and general system responsiveness in Windows.

Also, CB R20 is preferred as it's longer run-time heat-loads CPU and cooling enough to get a better picture. Intel hates it for the same reason, so prefers R15.