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How to actually improve PBO performance?

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post #1 of 54 (permalink) Old 10-21-2019, 09:01 PM - Thread Starter
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How to actually improve PBO performance?

Apart from getting better cooling, CPU Undervolt offset seem to hinder max clock speed on my system.
I am slowly trying to undervolt vddsoc and vddg to sane levels (now its at 1.04 vdsoc and 0.995 vddg) plus PLL undervolt to 1.7, this seems to help a bit.
Memories are ofcourse already overclocked to 3800 and tight timings.

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post #2 of 54 (permalink) Old 10-24-2019, 12:38 AM
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Best way is to have more than adequate cooling, best boost is achieved under 62-65c at full load. Depending on BIOS, there may be PBO setting for boost level (1 to 10) in my bios and max boost frequency (up to 200MHz), also TDP limits.
Make sure you have latest BIOS with AGESA 1003ABBA.

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post #3 of 54 (permalink) Old 10-24-2019, 05:03 PM
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Udervolting Ryzen 3000 reduces performance.


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post #4 of 54 (permalink) Old 10-24-2019, 05:34 PM
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Quote: Originally Posted by wingman99 View Post
Udervolting Ryzen 3000 reduces performance.
To be more accurate:
Undervolting Ryzen 3000 too much doesn't result in crashes. The chip can reduce reduce its workload to reduce power draw in an attempt to minimize Vdroop and not crash the processor. This obviously hurts performance. The thing is, its not always obvious that it's doing this Vdroop limiting trick and you'd only know by looking at benchmark results. See video for more.

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post #5 of 54 (permalink) Old 10-26-2019, 01:02 AM
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Quote: Originally Posted by wingman99 View Post
Udervolting Ryzen 3000 reduces performance.

https://www.youtube.com/watch?v=JscRwIH3OAY

From that video:



Notice how a -.1 Vcore voltage offset improved Cinebench score.

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post #6 of 54 (permalink) Old 10-26-2019, 10:26 AM
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Quote: Originally Posted by TELVM View Post
From that video:



Notice how a -.1 Vcore voltage offset improved Cinebench score.
Something is not correct with his testing, removing voltage level intern slowing of the transistor switch "on" time would not increase the score.

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post #7 of 54 (permalink) Old 10-26-2019, 05:09 PM
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Did you just claim that The Tech Jesus can't test correctly? Blasphemy! :-)

His testing is right. Most AM4 motherboards come OEM with the stock Vcore voltage a tad too high. Lowering the Vcore with a slight negative offset doesn't affect stability, but improves thermals. Ryzen CPUs then self detect the extra thermal headroom and increase frequency (or cancel/delay throttling down), resulting in slightly better performance.

My Ryzen 2600X also scores better with a -.1 Vcore offset.


If we continue lowering Vcore, below a certain threshold performance will drop like a brick. Hence the crappy scores @ 1V fixed Vcore in the chart above.

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post #8 of 54 (permalink) Old 10-26-2019, 08:12 PM
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Quote: Originally Posted by TELVM View Post
Did you just claim that The Tech Jesus can't test correctly? Blasphemy! :-)

His testing is right. Most AM4 motherboards come OEM with the stock Vcore voltage a tad too high. Lowering the Vcore with a slight negative offset doesn't affect stability, but improves thermals. Ryzen CPUs then self detect the extra thermal headroom and increase frequency (or cancel/delay throttling down), resulting in slightly better performance.

My Ryzen 2600X also scores better with a -.1 Vcore offset.


If we continue lowering Vcore, below a certain threshold performance will drop like a brick. Hence the crappy scores @ 1V fixed Vcore in the chart above.
That does sound possible. However, the single thread score of 3900X with -0.1v offset is less then stock performance and the processor should run cooler than multi-threaded where the performance increased over stock.

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post #9 of 54 (permalink) Old 10-26-2019, 08:17 PM
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My 2700x with 102 black bounces back and forth between 1.45 and 1.51 V crazy voltage man... but if that’s what AMD designed it for who am I to argue

I can’t see how the stock cooler can cool this thing with PBO on, my h100i platinum will get low 70s c

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post #10 of 54 (permalink) Old 10-26-2019, 10:05 PM
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Quote: Originally Posted by wingman99 View Post
Udervolting Ryzen 3000 reduces performance.

https://www.youtube.com/watch?v=JscRwIH3OAY
Hi @wingman99 I do not really use PBO or run any processor stock but I thought I'll check something just to see. I am posting two results below, first result is with PBO maxed out, or there about setting the cpu vcore to AUTO. The second result is exactly the same PBO setup with the cpu vcore offset to -0.1250 vcore. Firstly look at the temps in Hwinfo64 then obviously look at the results. I do believe negative voltage offset works great if you've manually overclocked your cpu and know what it is capable of at a certain vcore. In all honesty I can drop the vcore a little more with offset but I thought it is fine to begin with. Now to explain the results, with the vcore on auto I got a 100.4 x 41.74 dropping to 41.25 mostly during the run. With the 0.1250 vcore offset the processor was running 100.4 x 42 dropping just briefly to 41.5 but mostly running 41.75 multiplier.
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