PBO questions

[smoothnobody]

PBO allows the CPU to use more voltage so it can maintain boost frequency for longer, right? how does this work exactly? the 7800X3D boost is 4.5ghz. it can do this at stock voltage, no extra voltage necessary. how long it can boost depends on temperature. so how does giving it more voltage help? i kinda want to turn it off, cause allowing the CPU to use more voltage seems counter productive when undervolting. but i don't want to turn it off unless i'm sure i understand how it works. one thing i noticed, the curve optimizer menu in the bios is in the precision boost overdrive section. does this mean curve optimizer doesn't work unless PBO is on?

[freeagent]

You have an X3D chip, it is like owning a Dell where you cant really do much with it.

 

On my 58X3D I can use PBO to set my curve in CO, but the CPU is locked down, you need higher limits to get it to do more. You can lower them, but that sucks.. you would just lower raw performance.

 

I do not have AM5 so I do not know how locked down the chips are.

[Mark Kaine]

4 hours ago, smoothnobody said:

PBO allows the CPU to use more voltage so it can maintain turbo frequency for longer, right?

nope, wrong. it allows it to use less voltage and thus can maintain higher frequencies more often.

 

more voltage would just make it run hotter and downclock... you're looking at this from the wrong angle. 

 

4 hours ago, smoothnobody said:

turbo

nope! that's an intel thing,  ryzen doesn't have that. 

 

 

[smoothnobody]

linus video says it sends more power to the cpu. asus bios says it allows it to boost at higher voltages.

 

pretty sure curve optimizer allows you to adjust voltage curve, which people use to lower voltage, while PBO allows you to pull more voltage.

 

turbo/boost = xmp/expo same thing different words.

[TheDankKoosh]

PBO is an algorithm that uses on chip logistics and monitoring to best provide extra clock speed when more performance is requested by programs, also controlling when the chip needs to scale things back. This happens very quickly in few millisecond spans and is generally is optimal state of any Zen products after Zen 2. You generally cannot achieve equivalent light-load clock speeds when manually overclocking since the chip typically better determines when and how clock speed and voltage shifts need to happen. PBO can and will generally use higher voltages since the chip will be allowed to stretch it's legs from relaxed voltage and amperage requirements, this is not inherently harmful to the chips.

 

X3D chips have more stringent limits placed onto them due to the relatively fragile nature of the stacked cache, the extra cache also has the added deficit of running 10-15c hotter than their non stacked counterparts. As such these chips are multiple hundred megahertz short and limited to ~1.2v during heavy operation, at stock they tend to throttle slightly even if you're on a good cooler. Thankfully with the 7800x3d, AMD allowed support for one of the best PBO features Curve Optimizer, which allows you to adjust the voltage/frequency algorithm and effectively undervolt your CPU for every given frequency while still retaining the benefits of PBO itself. You'd likely see a 200-300mhz bump from just using curve optimizer to dial the algo down and give you the proper max clocks that your chip can handle at that same 1.2v limit. Hope this explains a majority of what you're looking to find with this topic.

 

25 minutes ago, smoothnobody said:

linus video says it sends more power to the cpu. asus bios says it allows it to boost at higher voltages.

 

turbo/boost = xmp/expo same thing different words.

Take it from me, someone who has watched for over 10 years, Linus has a generally poor understanding of hardware and there are far better sources to read/watch if you want something properly informative.

[smoothnobody]

gamers nexus says PBO effects 3 voltages, it allows the cpu to run beyond stock spec, it will raise the amount of power thats deliverable to the cpu, and maintain boost clocks longer.

 

i double checked his video to make sure i'm using the correct language. 

 

there was alot of confusion between precision boost and precision boost overdrive when they first launched. now that PBO2 launched and curve optimizer was introduced, there is more confusion between PBO2 and curve optimizer. i believe my previous comment is true, PBO was originally meant to run out of spec voltage and maintain boost longer. curve optimizer is used to adjust the voltage curve for lower voltage.

 

what i'm not sure about, is curve optimizer part of PBO, meaning i can't use curve optimizer without PBO, or do they function separately, meaning i can use curve optimizer without PBO.

[TheDankKoosh]

56 minutes ago, smoothnobody said:

what i'm not sure about, is curve optimizer part of PBO, meaning i can't use curve optimizer without PBO, or do they function separately, meaning i can use curve optimizer without PBO.

Semantics aside I believe PBO must be enabled for curve optimizer to take effect, as you are modifying the stock V/F curve of PBO for your chip. There is no inherent reason to disable PBO unless you're extremely temperature constrained in something like a passive system, otherwise adjusting the TDC, EDC and PPT to your liking is a much preferable option to retain performance.

[freeagent]

PBO will push the cpu harder. You should not be using PBO with stock power limits.

[Mark Kaine]

7 hours ago, smoothnobody said:

pretty sure curve optimizer allows you to adjust voltage curve, which people use to lower voltage, while PBO allows you to pull more voltage.

no. lower voltage = less heat = more performance (depending on silicone lottery,  some chips cant even do any undervolts)

there's no real diff what is used, pbo is preferable however. 

 

 

7 hours ago, smoothnobody said:

turbo/boost = xmp/expo same thing different words.

nope, completely different things.

 

turbo boost = intel feature 

 

xmp = automatic ram overclocking 

 

 

these things have like nothing to do with each other. ¯\_(ツ)_/¯ 

 

 

tldr: use pbo, test different settings  *extensively* if you want i can give you the best settings though... which will always be an undervolt as it just boosts more constantly.

 

 

[Mark Kaine]

6 hours ago, smoothnobody said:

PBO was originally meant to run out of spec voltage and maintain boost longer. curve optimizer is used to adjust the voltage curve for lower voltage.

again, no. these things do exactly the same things and on most chips/setups undervolt is the way to go!!

[freeagent]

1 hour ago, Mark Kaine said:

no. lower voltage = less heat = more performance

No, and I can prove it. The only way to truly undervolt is to do it with vcore, not curve or power limits. As soon as you enable PBO you have started to overclock.

[smoothnobody]

hey mark, can you provide any reference that PBO = less voltage? cause i think you are wrong. PBO = more voltage. curve optimizer = less voltage. here are my references that says PBO uses more voltage.

 

 

[Mark Kaine]

6 hours ago, freeagent said:

As soon as you enable PBO you have started to overclock.

no, because you can set a negative voltage offset,  which is the recommended way to do this (but obviously not the only way) the point is it takes 5 seconds and works (provided the chip isn't a lemon lol)

 

 

3 hours ago, smoothnobody said:

PBO = less voltage? cause i think you are wrong. PBO = more voltage

no i already explained it to you,  you're misunderstanding several things.

 

undervolting with pbo is incredibly easy, ive done it for years, same as my gpu (like literally) depending on bins it improves performance a lot (like 10%) and not just temporarily because it doesn't get too hot.

 

its apparently a common misunderstanding,  people think lower voltage = lower performance,  but ideally the opposite is the case!

 

 

 

[smoothnobody]

PBO is considered overclocking because you are running it beyond the manufacturers settings. AMD themselves said using PBO runs the chip outside of intended operation and voids warranty.

 

i'm not misunderstanding anything. i know what undervolting does. i've already done this with my cpu and gpu.

 

i'm not sure if your reading comprehension isn't good, or you are trolling. you seem to be the one who is confused about the purpose of this post. i'm not asking how undervolting works. i'm asking how PBO works, and if curve optimizer can be used without PBO. you claim PBO reduces voltage, while reputable people like steve linus and even asus themselves tells you in the bios PBO allows higher voltage. i've provided multiple references to support this. so unless you can back up your claims with some form of proof, i'm going to consider you a troll and disregard what you are saying.

[freeagent]

2 hours ago, Mark Kaine said:

no, because you can set a negative voltage offset

Once you do that, it starts to push the CPU upwards, it does not limit voltage in any way..

 

2 hours ago, Mark Kaine said:

the point is it takes 5 seconds and works (provided the chip isn't a lemon lol)

Exactly my point, you are relying on lottery to get more clocks with less voltage, which is why you would need to increase power limits to maintain stability. To some people if its good enough to game, its good enough.. but I am not like that at all.

[Mark Kaine]

18 hours ago, freeagent said:

Once you do that, it starts to push the CPU upwards, it does not limit voltage in any way..

... yeah, because that isnt the point of a negative voltage offset,  its to have lower temps,  more performance,  and ironically higher wattage on average. 

 

my 3600 without pbo: 65w  

 

with negative voltage offset (200): 135w ! 

 

18 hours ago, freeagent said:

Exactly my point,

and mine ~ 

 

 

21 hours ago, Mark Kaine said:

people think lower voltage = lower performance,  but ideally the opposite is the case!

 

[freeagent]

8 minutes ago, Mark Kaine said:

my 3600 without pbo: 65w

FYI, the 65w on the box comes at a stock static speed, not while boosting. For example: My 5900X says 105w on the box, that is at 3700MHz static, no boost.  With boost up to 143w. With my power settings in PBO, and my curve and boost override, that 143w turns into just over 250w PPT, and just over 260w package power. And with my settings, I guarantee my 5900X would be faster than your 5900X in everything.

[Mark Kaine]

1 hour ago, freeagent said:

FYI, the 65w on the box comes at a stock static speed, not while boosting. For example: My 5900X says 105w on the box, that is at 3700MHz static, no boost.  With boost up to 143w. With my power settings in PBO, and my curve and boost override, that 143w turns into just over 250w PPT, and just over 260w package power. And with my settings, I guarantee my 5900X would be faster than your 5900X in everything.

same principle,  but my 3600 at stock really never went above ~65w, that's why the change with pbo really surprised me...

 

it's basically idiot proof as long you follow the "instructions" (which was just a random reddit post lol)