can 6 phase VRM boards handle 3900X? would like feedback from people who tried it

[terroralpha]

hello,

i'm looking to build an ITX computer with a 3900X. i would like to use a B450/X470 board because they don't have any chipset fans. i have no use for PCI E 4 and don't need the extra heat and noise in this small case. however, i'm not sure if any of the existing B450/X470 boards can handle a 3900X going HAM while editing video or occasional gaming.

it looks like the 4xx boards with the best VRM are the asus B450 and MSI B450. both have 6 phase, 60A/phase VRMs. i'm not sure how the math works here but i do know that the 3900X has a 150W hard power limit. if i understand it correctly, the VRMs will work at around 1.2V, multiplied by 60A and then by 6 (# of VRMs). so, 1.2V x60A x6 = 432W max power delivery? does that mean that the B450 board will be OK with it long term?

i don't plan on hardcore OCing, but i will probably flip on PBO.

any ideas? or better yet, is anyone running a 3900X on a 6 phase VRM board?

 

[cucker tarlson]

good 6 phase ? of course.

 

[robot zombie]

Yep! Running mine on a Strix x370-f with 6 60A IR power phases and it runs on point. Just enabled PBO and it ran right up to expected performance. Still has more to give. No signs of strain on the VRMs whatsoever.

 

[cucker tarlson]

Yep! Running mine on a Strix x370-f with 6 60A IR power phases and it runs on point. Just enabled PBO and it ran right up to expected performance. Still has more to give.

that is true 6 phase and quality components
i'm a little afraid the op is talkling about 3 phase with a doubler on some crappy isl

for reference

AM4 Vcore VRM Ratings v1.4 (2019-11-07)

docs.google.com

 

[robot zombie]

that is true 6 phase and quality components
i'm a little afraid the op is talkling about 3 phase with a double on some crappy isl

Ooo yeah... that would be iffy.

EDIT: Removing bad info... I was remembering overclocking a different CPU, thinking my 3900x did over 200w when all I had to do was check my saved benches to see it was actually more like 125w. I need to not post at work, I think...

 

[Ozymandias]

AM4 Vcore VRM Ratings v1.4 (2019-11-07)

docs.google.com

I'm running a 3900X on an X370.
Admittedly it's on an VI Extreme which handles it with ease.

New AMD mid-year build

Build Log... [UPDATE 26/07/19] This build is now complete. :cool: The rest of the pretty pictures: https://www.guernsey-ci.com/public/ocuk/index.php?dir=New AMD Build Purchased. Fractal Design Arc Midi R2 ITX case (Picked up on clearance for next to nothing) Icy Dock ToughArmor MB607SP-B...

forums.overclockers.co.uk

Also running a 3900 (non-x) on a X570 TUF.

Shoe String Budget Build (Gaming Rig Upgrade)

[BUILD COMPLETE] This build is to replace and upgrade my ageing i7 6700k mITX gaming rig I built in 2016. So this build had under gone a few upgrades since the initial day one build in early 2020. But I think I'm finally at a point in mid 2021 where I can say that I'm happy where it is...

forums.overclockers.co.uk

[EDIT] Beaten to it.

 

[tabascosauz]

The Strix and MSI ITX B450s are just fine. 6 true Vcore phases with 40A and 60A PowIR respectively, IR35201.

The 3900X isn't that much a monster on power draw when not forced to run on fixed frequencies. As with anything without an active VRM fan, ensure decent airflow. PBO doesn't increase wattage much. Too many other limits in place

The Aorus ITX uses good components but the heatsink is subpar and it lacks on phases, making it a bit hot for >8 cores even with 50A PowIRs on IR35201 like the other two. The other ASRock B450 is utter trash.

These PowIRs are the top dogs of yesteryear. This X570 ITX generation is filled with brand spanking new IR TDAs and Vishay SPSes instead, but again, overkill on 3900X.

 

[terroralpha]

that is true 6 phase and quality components
i'm a little afraid the op is talkling about 3 phase with a doubler on some crappy isl

for reference

AM4 Vcore VRM Ratings v1.4 (2019-11-07)

docs.google.com

i'm not. the two boards i mentioned are both true 6 phase VRM boards. those are the only two 4xx series boards i'm looking at. going to avoid asrock like the plague this time around due to their junk VRM.

The Strix and MSI ITX B450s are just fine. 6 true Vcore phases with 40A and 60A PowIR respectively, IR35201.

oh damn, good call. i thought all the phases on the asus were 60A, turns out it was only the SOC VRM that's 60A. looks like i'll be buying my first ever MSI board.

 

[tabascosauz]

oh damn, good call. i thought all the phases on the asus were 60A, turns out it was only the SOC VRM that's 60A. looks like i'll be buying my first ever MSI board.

I mean, I'm not sure you'll ever even get close to 40Ax6=240A of power draw on a PB 3900X...the new TDA21472 (70A) equipped X570 boards are beginning to approach "too-good" territory, where the hardware spends the vast majority of its time in a power band where the efficiency is actually undesirable on the new smart power stages. Remember that all of these PowIRs and SPSes are rated for maximum current, and that you'll have to get within throwing distance of that number to actually achieve peak efficiency. Too overkill / too little power draw and they're actually not very efficient.

Depends on what you're after, I guess. I'll never opt for for a board that places an NVMe M.2 on the back of the board (the MSI ITX). The Strix has got two 3.0 x4s, but the second shares bandwidth with the x16 slot. MSI also has a shittier wifi card (not hard to replace) than the Aorus and Strix, as well as shittier LAN (the other two have i211), but it's not a big deal for most people. The big selling point of the Strix and MSI are the extra two true phases, which really reduce the heat on the pitifully designed heatsinks that all 3 of them have.

 

[JackCarver]

Get the MSI B450I Gaming with 60A power stages. The two Ryzen 3900X/3950X have 95A-140A current draw. 95A most of the time with spikes to 140A. If you do a little overclocking it will be higher. If you look at the efficiency graph of the IR 40A and the IR 60A power stages you see, that the efficiency of the 60A stages is better with 6 phases than the efficiency of the 40A stages:

With 100A current output every phase has to handle 17A, so you are still in a very good efficiency here. Power Loss and heat dissipation is here less than 2 Watts per stage.
With the 40A stages of the Asus Board it looks like:

So with 17A per stage efficiency is not as good as with 60A stages as you can see. Power Loss is here at 2 Watts per stage. So with overclocking the 60A stages will be way better here.

Edit:
If you choose another brand then no problem, but be sure to get 60A stages.

 

[terroralpha]

@tabascosauz i was going to say that, according to my memory, the bigger power stages should be more efficient overall even at low power draw, and therefor output less heat in to the ITX chassis i'll be putting this in. @JackCarver posted the actual efficiency charts just above me. the difference is small, the 60A stages are about 2%-3% more efficient, but they have more headroom.

looks like a 3900X with PBO will have the 40A stages running at about 50% load, that will probably torpedo the life of the board. 60A is probably the better choice here.

i'll probably be replacing the heatsink on whichever board i get with a proper one.

 

[tabascosauz]

@tabascosauz i was going to say that, according to my memory, the bigger power stages should be more efficient overall even at low power draw, and therefor output less heat in to the ITX chassis i'll be putting this in. @JackCarver posted the actual efficiency charts just above me. the difference is small, the 60A stages are about 2%-3% more efficient, but they have more headroom.

looks like a 3900X with PBO will have the 40A stages running at about 50% load, that will probably torpedo the life of the board. 60A is probably the better choice here.

i'll probably be replacing the heatsink on whichever board i get with a proper one.

You don't need to go those kinds of lengths; this isn't AM3+. Just get some air moving over the heatsink and you'll be plenty fine.

What case is this going into, and what is the 3900X cooled with? Anything larger and traditionally laid out like a QBX or H200i, just treat it as you would any other ATX build.

 

[terroralpha]

You don't need to go those kinds of lengths; this isn't AM3+. Just get some air moving over the heatsink and you'll be plenty fine.

What case is this going into?

fully watercooled node 202. see attached picture.

it's currently running an overclocked 8600k + RTX 2080 super.

 

[JackCarver]

@tabascosauz i was going to say that, according to my memory, the bigger power stages should be more efficient overall even at low power draw, and therefor output less heat in to the ITX chassis i'll be putting this in. @JackCarver posted the actual efficiency charts just above me. the difference is small, the 60A stages are about 2%-3% more efficient, but they have more headroom.

looks like a 3900X with PBO will have the 40A stages running at about 50% load, that will probably torpedo the life of the board. 60A is probably the better choice here.

i'll probably be replacing the heatsink on whichever board i get with a proper one.

With stock settings the 40Amps stages will be enough, but with oc and spikes to 200Amps for example every stage has to handle 33,33A. The 60A stages are still in the 90s here with about 18W heat dissipation. The 40A are at 86% with 36W heat dissipation. So a good heatsink is here definitely necessary.

 

[tabascosauz]

fully watercooled node 202. see attached picture.

it's currently running an overclocked 8600k + RTX 2080 super.

@terroralpha Is that a Z390 PG/ac? If you're not having any thermal problems overclocked on that toasty power delivery setup, you won't have any trouble here. It really isn't that beefy, save for the heatpipe which is of limited usefulness in that application. But short of some hard 9900K OC it's just fine with some airflow; same goes here for the 6-phase MSI. Even if you replace the Vcore heatsink with aftermarket copper ones a la AM3, if your case is airflow limited it won't do you a lot of good. A good ol' fan goes a long, long way.

@JackCarver Also, I'm not sure where this "200A spikes" number is coming from. Do you own a Zen 2 platform? Stock EDC (short-term) limit is 140A; PBO won't take his chip far past that, you have to run fixed freq for that. And like I've said a billion times, fixed freq is not the way to go.

 

[terroralpha]

Is that a Z390 PG/ac? If you're not having any thermal problems overclocked on that toasty power delivery setup, you won't have any trouble here.

Yep, I had no problem with it. But that board has a beefy heatsink on the CPU VRM

 

[lexluthermiester]

hello,

i'm looking to build an ITX computer with a 3900X. i would like to use a B450/X470 board because they don't have any chipset fans. i have no use for PCI E 4 and don't need the extra heat and noise in this small case. however, i'm not sure if any of the existing B450/X470 boards can handle a 3900X going HAM while editing video or occasional gaming.

it looks like the 4xx boards with the best VRM are the asus B450 and MSI B450. both have 6 phase, 60A/phase VRMs. i'm not sure how the math works here but i do know that the 3900X has a 150W hard power limit. if i understand it correctly, the VRMs will work at around 1.2V, multiplied by 60A and then by 6 (# of VRMs). so, 1.2V x60A x6 = 432W max power delivery? does that mean that the B450 board will be OK with it long term?

i don't plan on hardcore OCing, but i will probably flip on PBO.

any ideas? or better yet, is anyone running a 3900X on a 6 phase VRM board?

Do you have a specific board in mind? If it is of sufficient quality, 6-phase power will do fine.

 

[terroralpha]

Do you have a specific board in mind? If it is of sufficient quality, 6-phase power will do fine.

yep, i mentioned both of them in the OP. asus B450 ITX and msi B450 ITX. will be going with the MSI

 

[lexluthermiester]

yep, i mentioned both of them in the OP. asus B450 ITX and msi B450 ITX. will be going with the MSI

You didn't mention board make or models, thus my comment. Not all B450 boards are made equal. I've seen budget models that have only 4-phase power to the CPU.

 

[tabascosauz]

You didn't mention board make or models, thus my comment. Not all B450 boards are made equal. I've seen budget models that have only 4-phase power to the CPU.

He said he wanted to build ITX. He said he was looking for B450. There are only 4 choices there, one of which is trash, one of which is unsuitable for >8 cores, and two that are actual contenders.

@terroralpha I hope you don't mind audio / have a better audio solution ready. MSI one is ALC887, a name I haven't seen in a long, long time.

 

[terroralpha]

He said he wanted to build ITX. He said he was looking for B450. There are only 4 choices there, one of which is trash, one of which is unsuitable for >8 cores, and two that are actual contenders.

@terroralpha I hope you don't mind audio / have a better audio solution ready. MSI one is ALC887, a name I haven't seen in a long, long time.

Nope. Don’t care. I’m using a Bluetooth headset anyway. Even if there was no audio output at all i wouldn’t care. Thanks for the heads up though.

 

[Durvelle27]

3900X worked just fine on my B350 Board

 

[lexluthermiester]

He said he wanted to build ITX. He said he was looking for B450. There are only 4 choices there, one of which is trash, one of which is unsuitable for >8 cores, and two that are actual contenders.

I found 6 that meet the requirements stated in the OP.

ASRock B450M Steel Legend AM4 Micro ATX Motherboard - Newegg.com

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MSI Performance Gaming B450I Plus AC Mini ITX Motherboard - Newegg.com

Buy Used - Like New: MSI PERFORMANCE GAMING B450I GAMING PLUS AC AM4 AMD B450 SATA 6Gb/s Mini ITX AMD Motherboard with fast shipping and top-rated customer service. Once you know, you Newegg!

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ASUS ROG STRIX B450-I GAMING AM4 Mini ITX AMD Motherboard - Newegg.com

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GIGABYTE B450 I AORUS PRO WIFI AM4 Mini ITX AMD Motherboard - Newegg.com

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ASUS TUF X470-Plus Gaming AM4 ATX AMD Motherboard - Newegg.com

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Every one of these will work well for the OP's needs.

 

[JackCarver]

VRM wise the MSI B450I Gaming is the best.

 

[Zach_01]

A 3900X will hit the 140A on heavy all core load. This is the first PBO limit the CPU finds, called EDC “Electrical Design Current”. Even with manual PBO settings and released EDC (you can set it to 1000A if you like) the CPU hardly will surpass it. And if it is, by a small margin. This is not allowed by the silicon controller. There is no way around that unless a static OC take place, and anything is possible. I don’t recommend...

Other PBO limits
PPT (Package Power Tracking =Total socket power draw)
TDC (Thermal Design Current)

TDC (90A) is irrelevant below temperature throttling threshold of 95C.

PPT for 3900X is 140W and it’s not easy to hit the value unless static OCed or in auto boosting under low temperatures. Around 70-75C will be around 135W. If you manage to cool it down, under 70C, EDC will also drop and will allow more clock and voltage and it may hit the 140W PPT limit.

If you uncap PPT with manual PBO settings (like 145W) it will pass 140W if EDC and temp is allow this.

If you cap EDC to 135A or 130A or even more then the PPT will almost certainly surpass the 140W (with more clock/voltage) as long as you give it headroom by setting it 145W or 150W. Again, temperature must allow this.

More or less this is the function of ZEN2 silicon FITness controller.