# How relevant are VRMs (phases) for AM4 motherboards?



## Absolution (Feb 26, 2017)

Just wondering ... why are VRMs relevant in this generation? I remember it being a thing to look out for when looking for FX8350 processors, but when looking for a 6700k, this wasnt something that was discussed in the Intel mobo circles..

Does it still apply to newer gen lower TDP CPUs?


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## natr0n (Feb 26, 2017)

Vrms stuff was integrated into the intel chips from what I read so less were used on boards.

As for new amd chips and vrms on boards you would assume we dont know till reviews.


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## FR@NK (Feb 26, 2017)

No one really know just yet because we dont have Zen processors to play with. I would guess we are gunna need beefy VRMs if we want to get good overclocks on the new 8 core chips. My 8 core intel only pulls ≈100 watts while gaming at 4.5GHz. I think the lower end AM4 boards might have issues at this power level. I've seen 160+watts running heavy AVX2 work loads at 4.3GHz.


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## lukart (Feb 26, 2017)

Looks like Gibbo from Overclockers shop saying that he strongly recommends the X370 Crosshair or Taichi for 4Ghz+ overclocking on all 8 cores.


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## Vya Domus (Feb 26, 2017)

Depends whether or not you plan on overclocking , if you don't most likely you can throw the 1800x even in a lower end motherboard and not encounter any problem. If you want to overclock things might get ugly , no one knows how clock rates scale  with power consumption , these things are usually not linear and in order to achieve a certain overclock you might need some beefy VRM configuration and cooling.



lukart said:


> Looks like Gibbo from Overclockers shop saying that he strongly recommends the X370 Crosshair or Taichi for 4Ghz+ overclocking on all 8 cores.



That's nothing more than a guess , until people get these things up and running and start pushing them no one can say for certain.


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## EarthDog (Feb 26, 2017)

I'm going to say yes. Considering the lack of scaling from 4ghz stock to requiring ln2 in order to hit 5ghz, I think it scales power/temps up pretty quickly...

These aren't going to do much more than 4.3-4.4ghz on WATER (all cores).



Vya Domus said:


> Depends whether or not you plan on overclocking , if you don't most likely you can throw the 1800x even in a lower end motherboard and not encounter any problem.


well, you'd think that was true, but it isn't. Sadly, there were dozens of amd boards which said it supported the 8370 only to end up throttling at stock speeds because of toasty socket and vrms. This is why the thread is quite a valid question.


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## Vya Domus (Feb 26, 2017)

EarthDog said:


> well, you'd think that was true, but it isn't. Sadly, there were dozens of amd boards which said it supported the 8370 only to end up throttling at stock speeds because of toasty socket and vrms. This is why the thread is quite a valid question.



But that was a 125W cpu (and that value was very optimistic) 95W cpu's should have no problem on basic 4+1 phase boards unless the TDP AMD provided is way off from what it is in reality and the board is absolute shit.


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## EarthDog (Feb 26, 2017)

Yep... knew that. My answer doesn't change. 

I'm hoping you are right, but wouldn't bet on it from what I've seen.


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## Vario (Feb 26, 2017)

More and better power phases is always important for OC.


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## TheoneandonlyMrK (Feb 26, 2017)

Vya Domus said:


> But that was a 125W cpu (and that value was very optimistic) 95W cpu's should have no problem on basic 4+1 phase boards unless the TDP AMD provided is way off from what it is in reality and the board is absolute shit.


Tdp is not power in, its max heat out so it doesn't really indicate vrm quality required or anything similar. 
You want 8 cores your going to need power or is Intel's hedt platform more special then I am aware of, seams like a shit moaning thread to me , you want solid performance unfettered by throttling ,pay the money it's simple and fair and,
Consistent across chip manufacturers, as are vrm designs.


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## Vya Domus (Feb 26, 2017)

theoneandonlymrk said:


> Tdp is not power in, its max heat out so it doesn't really indicate vrm quality required or anything similar.



The TDP manufacturers quote isn't an independent value it's very closely related with power consumption which is relevant for nominal VRM requirements. It's why motherboard manufacturers list CPU support by " up to x TDP"  in conformity with the number of phases and their quality. It's good enough of an indicator , of course in lack of any other more precise information which I doubt they'll ever provide officially.

Of course whoever buys into this platform should definitely go for higher end boards there is no question about that , but given it's price you'll see a good amount of people sticking with lower end ones thinking it must be enough , it's bound to happen and they probably know it.


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## TheoneandonlyMrK (Feb 26, 2017)

Vya Domus said:


> The TDP manufacturers quote isn't an independent value it's very closely related with power consumption which is relevant for nominal VRM requirements. It's why motherboard manufacturers list CPU support by " up to x TDP"  in conformity with the number of phases and their quality. It's good enough of an indicator , of course in lack of any other more precise information which I doubt they'll ever provide officially.
> 
> Of course whoever buys into this platform should definitely go for higher end boards there is no question about that , but given it's price you'll see a good amount of people sticking with lower end ones thinking it must be enough , it's bound to happen and they probably know it.




To me you should buy after some close deliberation over what you want and what you can afford, after reading reviews I got a good board last time I didn't expect something to not draw more power if pushed to it's max or beyond and I wouldn't if I bought Intel either.
CPU power control and delivery as well as clock control is largely software and sensor based these days, it's a change but it already allows for higher GPU clocks out of the box for all not just elitist clockers but also brings in new lately thermal based limits or power delivery limits on most systems , again that's not new really.
This is just the next episode, there will be much to moan about but most should be better served by these new ways of doing things.


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## L1amrob (Feb 27, 2017)

Might be the case that the asrock has 16power phases? I seen somewhere not sure where....


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## EarthDog (Feb 27, 2017)

I believe their flagship does, yes.


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## londiste (Mar 10, 2017)

i think this has been linked a couple of times around tpu forums, but there are pretty detailed graphs about voltage/power scaling of ryzen:
https://forums.anandtech.com/threads/ryzen-strictly-technical.2500572/

looks like for anything above stock, especially if looking for the oc in the feasible 4.0/4.1ghz range, you'd want as robust power bits of motherboard as possible.


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## RejZoR (Mar 10, 2017)

The more the better. It's a beefy multi-core CPU, treat it well by providing it with stable power delivery.


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## r9 (Mar 10, 2017)

More VRM phase equals smoother power output not necessary higher output.
It depends on the power rating of the mosfets used.
If the rating of the mosfets used are the same of the 3 vs 6 phase VRM then you proportionally you get double the power output.
But if you have 6 phase mosfets that are half of the rating of the 3 phase ones then the potential power output would be the same.
And in that case 6 phase would provide smoother power but provable be more fragile.


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## dorsetknob (Mar 10, 2017)

Vya Domus said:


> but given it's price you'll see a good amount of people sticking with lower end ones thinking it must be enough , it's bound to happen and they probably know it.



Given time  there will no doubt be the same sort of threads bemoaning Motherboard Overclocking/overheating issues due to the low VRM phase count ect ( in the Same way people had problems with 125w AMD chips in a board rated for 95w)

and i'm not kicking AMD it happened in the current /past and logic says its going to be thread material in the Future


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## Aenra (Mar 10, 2017)

dorsetknob said:


> Same way people had problems with 125w AMD chips in a board rated for 95w



Yes...


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## RejZoR (Mar 10, 2017)

r9 said:


> More VRM phase equals smoother power output not necessary higher output.
> It depends on the power rating of the mosfets used.
> If the rating of the mosfets used are the same of the 3 vs 6 phase VRM then you proportionally you get double the power output.
> But if you have 6 phase mosfets that are half of the rating of the 3 phase ones then the potential power output would be the same.
> And in that case 6 phase would provide smoother power but provable be more fragile.



It's also a matter of generated heat and lifetime. If you have few powerful mosfets, you're concentrading a lot of heat as you pull amps from them. If you spread them out and they even have a cooler on, they'll run cooler and as they are cooler, they deliver more power (which drops the hotter they are). If you have more of them beyond reference design, it also means they'll be under less stress and the whole circle kinda unwraps itself instead of looping in the same circle of perpetual "problems" that are connected to one another. This especially applies when overclocking powerful CPU's and you want to run them like that for years...


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## cdawall (Mar 10, 2017)

r9 said:


> More VRM phase equals smoother power output not necessary higher output.
> It depends on the power rating of the mosfets used.
> If the rating of the mosfets used are the same of the 3 vs 6 phase VRM then you proportionally you get double the power output.
> But if you have 6 phase mosfets that are half of the rating of the 3 phase ones then the potential power output would be the same.
> And in that case 6 phase would provide smoother power but provable be more fragile.



A lot of that has to do with quality of mosfets and drivers used. You can have a great 4+1 design that provides smooth clean power and a terrible 8+2 design that throttle at stock and is all over the place. Absolutes don't work in the tech world.


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## r9 (Mar 10, 2017)

cdawall said:


> A lot of that has to do with quality of mosfets and drivers used. You can have a great 4+1 design that provides smooth clean power and a terrible 8+2 design that throttle at stock and is all over the place. Absolutes don't work in the tech world.


Design and quality gonna play big part.
My post was under assumption that we have scenario with equal quality VRM.
More phases you have the more they overlap and rely less on the post VRM capacitors to smooth the power.


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## r9 (Mar 10, 2017)

RejZoR said:


> It's also a matter of generated heat and lifetime. If you have few powerful mosfets, you're concentrading a lot of heat as you pull amps from them. If you spread them out and they even have a cooler on, they'll run cooler and as they are cooler, they deliver more power (which drops the hotter they are). If you have more of them beyond reference design, it also means they'll be under less stress and the whole circle kinda unwraps itself instead of looping in the same circle of perpetual "problems" that are connected to one another. This especially applies when overclocking powerful CPU's and you want to run them like that for years...



If both 4+1 and 7+1 have same TDP rating. 7+1 not gonna provide better longevity.
That can only mean that the mosfets in 7+1 have lower rating means they need to work harder for shorter time.


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## cdawall (Mar 10, 2017)

r9 said:


> Design and quality gonna play big part.
> My post was under assumption that we have scenario with equal quality VRM.
> More phases you have the more they overlap and rely less on the post VRM capacitors to smooth the power.



We don't live in a perfect world you won't really see situations like that. Most of what you will see in the real world are high end board with anything from an 8+2 to 16+2 mosfets arrangement and low end boards with 3+1 setups.

It is already long since been proven that these new chips will not favor overclocking on low end mosfets.

And to be fair to RejZoR a 7+1 with the same tdp rating will likely last longer than a 4+1, more surface area to cool means typically lower temperature especially since each fet will have less load run directly through it producing less heat individually.


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## r9 (Mar 10, 2017)

cdawall said:


> We don't live in a perfect world you won't really see situations like that. Most of what you will see in the real world are high end board with anything from an 8+2 to 16+2 mosfets arrangement and low end boards with 3+1 setups.
> 
> It is already long since been proven that these new chips will not favor overclocking on low end mosfets.
> 
> And to be fair to RejZoR a 7+1 with the same tdp rating will likely last longer than a 4+1, more surface area to cool means typically lower temperature especially since each fet will have less load run directly through it producing less heat individually.



And to be fair to all the people on the forums that never ever touched multi-meter or a rework station and go by the manufacturers marketing materials. 
Take it form someone that did chip level repairs motherboards, graphics cards, monitors, psu and laptops.
More complex VRM solutions are far more common to fail.
And most of the time is the resistor or capacitor in the protection circuit of the VRM that fails not the mosfets.
I will give the cooling benefit of having more phases.
But people need to understand that the failure doesn't happens during normal operation.
It happens when for whatever reason there is unexpected high power draw that will happen and takes only 1 ms.
That load will not be spread equally through all the mosfets, its one phase at a time.
It will hit one pair of mosfets of the phase being used at the time.
The low phase mosfets will have higher ratings and higher chance to survive the load.


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## cdawall (Mar 10, 2017)

You see more high phase count boards for repair because low end boards with low phase count mosfets go in the trash. It cost more to repair one than it is worth. On top of that low end boars end up in low end systems with low end CPU's. Less power draw, less heat, no overclocking, less prone to abuse and failure. 

Even Dell uses h/z170/270 boards in their products with i7's. 

We are also seeing a lot of high end boards move to an all in one solution so there is no longer a high and a low side. Same thing on graphics cards.


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## RejZoR (Mar 10, 2017)

The problem with mosfets is that amps output is directly connected to temperature at which they operate. And they tend to operate at fairly high temperatures even under perfectly normal conditions.

*Made up example:*
If mosfets rated at 80A at 60°C, will only output 45A at 80°C. At 100°C it will only output 20A. And then you have a problem...


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## Evo85 (Mar 10, 2017)

VRM's are always relevant across any platform. If you having cleans table, steady power that is.


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## cadaveca (Mar 10, 2017)

Evo85 said:


> VRM's are always relevant across any platform. If you having cleans table, steady power that is.


but on Z270/Z170, because power draw is so low on 24/7 OC (125~150W), it isn't as important as on X99 or AM4, where OC power consumption can reach 300W.


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## SliceT (Mar 14, 2017)

Even Gibbo, Overclockers shop said the best X370 to get would be the crosshair and Taichi, both with strong power phases..


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## johnspack (Mar 14, 2017)

Relevant for any mobo.  It's the difference between 4.6 on air and 5.0.  Cleaner,  higher amperage power delivery is always best.  I'm stuck at 4.6 on this 8 phase mobo,  on a 16 phase I could prob get 4.8 before water cooling....
5.0 or higher on custom water cooling....


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## EarthDog (Mar 14, 2017)

johnspack said:


> Relevant for any mobo.  It's the difference between 4.6 on air and 5.0.  Cleaner,  higher amperage power delivery is always best.  I'm stuck at 4.6 on this 8 phase mobo,  on a 16 phase I could prob get 4.8 before water cooling....
> 5.0 or higher on custom water cooling....


.... maybe... you are putting too much into it. Intel needs it, even using x79/x99, much less than amd. I'd bet you are limited by voltage or temps to 4.8+ before your board holds you back.


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