Ryzen 5000 Undervolting with PBO2 – Absolutely Worth Doing

under vaulting a processor whether that's your cpu or your gpu can have huge benefits for your system lower voltage means better power consumption which in turn means better system temperatures and noise levels but when it comes to undervolting a ryzen processor you're not really left with any good options that is until now today we're taking a look at the new update to precision boost overdrive an amd feature that was exclusively used for overclocking but now includes under vaulting and i've just gotta say it works incredibly well if you have a ryzen 5000 cpu on hand there's basically no reason why you wouldn't use this so let's take a look at what you need to know so just to recap up until now undervolting on amd ryzen has been a bit broken typically you'd expect to just enter in a negative voltage offset of say minus 100 millivolts like you can with an intel cpu then have the benefit of the processor operating cooler using less power but at the same boost frequencies that's how it's worked on intel for years now but that's not what we've seen on amd ryzen instead when only lowering the voltage you get some really odd and unexpected behavior where the undervolt appears to be stable clock speeds appear to be stable as well but you actually get significantly decreased performance this left you with only one option and that's a hard frequency and voltage cap for example manually setting something like 4 gigahertz at 1.12 volts although there you might get the improved thermals in those heavier workloads this means that the cpu can't boost beyond that frequency in those lighter threaded workloads like gaming and everyday tasks so the new update aims to fix all of that which is great but before we dive headfirst in and start adjusting a bunch of settings let's first understand what we're adjusting in the first place so the way that processors manage their own performance and power is based off of a frequency and voltage curve they need higher voltages to stabilize higher frequencies whereas lower clock speeds can get away with significantly less voltage amd ryzen 5000 processors for example typically operate between 1.1 and 1.5 volts with clock speeds between 4.2 and 5 gigahertz in that range depending on the cpu another very important note and something that does get mixed up quite a bit it's the less demanding workloads that use one or two cores operating at higher voltages and higher clock speeds whereas the all core workloads the heavier ones like rendering that's where you'll see lower voltage and lower clock speeds across all cores the cpu has to use those lower clock speeds and lower voltages to stay within a certain power threshold whereas that power threshold really isn't a factor when you're only loading one or two cores so those higher frequencies and higher voltages become available now processors out of the box operate a bit more on the safe side in terms of voltage and clock speeds to give the user the most stable experience possible in other words the voltage and frequency curve is a pretty comfortable one at stock this is why usually we also have quite a lot of breathing room when it comes to overclocking and under vaulting so the aim of undervolting then is to essentially take this stock voltage and frequency curve and shift it downwards this pushes the processor to use lower voltages at a given clock speed or from a different perspective higher clock speeds at a given voltage and this is exactly how we'll be adjusting the precision boost overdrive 2 with a new feature called curve optimizer you can basically just think of this as offsetting the default voltage and frequency curve of the cpu in the positive direction if you want to overclock and then in the negative direction if you want to undervolt this can be accessed within the bios of the 500 series motherboards but the bios also needs to be updated to one with at least the giza 1.1.8.0 firmware so in short it's 500 series motherboards only that we'll be able to do precision boost overdrive too and even then some of them don't even have the required bios update and firmware update for example my asus x570 crosshair 8 impact in my own production system doesn't have the update available whereas the msi x570 creation i use for testing has 1.1.9.0 so some boards are going to be a lot more up to date than others so definitely check the board that you have on hand and probably the most unfortunate news is that this is only going to be for ryzen 5000 only and i did attempt this with a ryzen 3000 processor but the options in the bios were just unfortunately invisible so not sure if this is an architectural limitation or if just amd is just hard capping this for ryzen 5000 either way i would have loved to see some backwards compatibility here but moving on in the bios of the msi x570 creation we need to head over to the advanced cpu settings then amd overclocking there we can enable precision boost overdrive and select advanced the next very important setting before doing anything else is setting pbo limits to disabled what this does is instead of raising the power limit and current limit values of the cpu as it normally does with precision boost overdrive selecting disabled here actually forces the stock power profile of the processor then to actually start making adjustments we need to climb into curve optimizer there we're going to select negative indicating that we want to lower the voltage and frequency curve then we enter in the magnitude that we want to adjust the curve in this field right here each unit of value here represents three to five millivolts and at least with this bios and board i can enter in a max of 30. that represents a negative voltage offset between 90 and 150 millivolts and i think the exact value would depend on which area of the curve we'd be looking at so i tested this with the six core 5600 x the 12 core 5900x and the 16 core 5950x both the 5600x and 5900x passed through all of the testing with the max value here of 30 but the best undervolt that i could do with the 5950x was with a value of 12. and i think that's because the 5950x is already using a fairly optimized voltage and frequency curve and can't really be pushed beyond that so now with the negative curve offset enabled you would expect lower voltages and power at the same frequency and performance as that's what we expect from undervolting but that's actually not what we get instead since voltage is lowered and power consumption is lowered as a result of that as well the cpu sees that it has a lot more headroom before hitting its power limit and so it uses that power and increases the clock speed as an example check this out here we're running blender comparing the 12 core ryzen 9 5900x at stock in orange to the max under vault that we can achieve with pb02 with a negative offset of 30. the first graph that we see here voltage is basically the same eventually leveling out to about 1.2 volts although pbo2 is slightly lower overall doesn't peak as much in the beginning and has lower troughs then looking at power in the middle expressed as a percentage of the total power limit used it's pretty much even but then when we take a look at clock speeds we're basically getting a free 200 megahertz overclock that is we're running almost 200 megahertz faster across all 12 cores at no additional cost to power draw which also means no additional thermals both the processor at stock and with the precision boost to undervolt in effect the cpu regulates itself to pull 100 of its available power so thermals are about equal between them now the result is a little bit different when we switch to only using a single core in cinebench r20 as opposed to loading all of them in the previous test now instead of the 5900x pulling up to 1.48 volts on a single core it only pulls 1.37 power is also reduced as a result down to 39 from around 48. oddly though we do actually get a minor clock speed boost as well so in lighter threaded workloads effectively we get a slightly faster slightly cooler running processor pulling less power comparing thermals though we can now see a big difference that single coil all of a sudden isn't so power or voltage hungry and runs up to nine degrees cooler as a result again we're actually running slightly faster clock speeds here as well with a bit of a higher score in cinebench we'll take a look at that in just a minute as i mentioned the undervolting results with the 5950x were a bit underwhelming i was only able to set a curve offset of -12 but this still gave us around a 100 megahertz all core improvement at the same power and voltage the 6 core 5600x results were pretty similar to the 5900x again similar voltage levels but with the pbo2 results offering a lower voltage peak in the beginning of the render when it's loading assets then power consumption is dead even between the two and clock speeds are close to 200 megahertz higher across all six cores so what does this mean in terms of actual performance gained well in cinebench r20 with all cores enabled the ryzen 5600x gains around eight percent with a precision boost to undervolt the 5900x gains around four percent and the 5950x only gains around one percent because again we couldn't offset the curve as much the performance gains in blender were pretty similar six percent improvement for the 5600x seven percent for the 5900x and then four percent for the 5950x it's nothing huge you'd definitely be able to get more than this with a manual overclock and more power but this is at equal power and thermals it's essentially free performance loading only a single core though we get some performance gains here as well but the main benefit here if you remember was the significantly less voltage and power being fed to that single working thread resulting in better thermals still though there are some very small performance improvements here to enjoy as well so it's a win-win gaming performance on the other hand i did not measure any improvements in at all when it came to gains in fps and just like our single threaded cinebench test the main benefit here is going to be the cpu voltage and power not spiking as high as it would at stock so for gaming expect slightly better thermals and power from your cpu but about equal performance so honestly this is looking like an incredible feature for ryzen 5000 users to take advantage of essentially what we're getting is in all core workloads a free 200 megahertz overclock and then in those liner threaded single core workloads a very slight increase in clock speeds but more importantly lower thermals voltage and power if on the other hand you want to undervolt traditionally to achieve lower thermals across the board you'll also need to reduce the ppt or power limit of the cpu because the processor auto regulates its clock speeds around its power limit that's what you'll need to reduce in addition to the negative curve offset to prevent the processor from essentially overclocking itself to meet the power limit i'm a bit annoyed that this isn't available on even my own machine that uses a very expensive motherboard just yet but i'll definitely be keeping an eye out for future bios updates so there it is precision boost overdrive 2. it's definitely worth checking out if you have a ryzen 5000 processor and i'll definitely be using this for future ryzen 5000 build i'd love to know your thoughts down below in the comments as always a huge thanks for watching and i will see you all in the next one

Channel: Optimum Tech

Views: 1,142,396

Keywords: amd, precision boost overdrive, PBO, precision boost overdrive 2, pbo2, overclocking guide, ryzen, undervolting, Ryzen 5950X, Ryzen 5900X, Ryzen 5600X, optimum tech, how to undervolt amd ryzen

Id: dfkrp25dpQ0

Length: 11min 18sec (678 seconds)

Published: Sat Jan 09 2021