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VRM on the new AM4 motherboards - Page 153

post #1521 of 1994
Quote:
Originally Posted by AlphaC View Post

Quote:
Originally Posted by cssorkinman View Post

25 amps 1 volt = 25 watts - 4.23 calculated lost = 20.77 = 83 % Where did I go wrong?

All graphs for NexFets are for 1.3V. Also for 4GHz most people are using 100 - 110A not 150A.

The quick and dirty way would be > 91% efficiency based on NexFET Power block performance on that graph , for 1.3V only.

Efficiency = Power out /power in = (P_in-P_loss)/P_in = P_out / (P_out+P_loss)
For 150A (25A output current *6 phases), 1.4V the loss would be :
below 4W per phase (per graph figure 1) x 1.025 normalization factor (figure 8 for 1.4V) = 4.1W per phase
Power loss for 6 phases = 4.1W x 6 = 24.6W ---> round to 25W
Power out = 1.4V x 150A = 210W

efficiency = 210W/(210+25W) = 0.8936 .... = above 89.3%
Quote:
Originally Posted by bardacuda View Post

What's the downside? I think the CPU clock limit might be related to droop. If SVI 2 is my drooped voltage then I'm losing like 75mV. I'm hoping a new BIOS fixes it. I've already tried LLC 2 and 3 and they're unstable.

Lower switching frequency results in higher potential ripple. However the X370 prime pro has a rather large capacitor bank. It has over 5K uF at the V_core side , albeit 5k hour rated caps.



Some more possible capacitance ratings: Warning: Spoiler! (Click to show)
Gigabyte GA-AB350-Gaming 3: 5KW29 560 6.3V
6 x 560uF= 3,360μF
https://content.hwigroup.net/images/products_xl/386364/gigabyte-ab350-gaming-3.jpg , http://www.creativecomputing.net/images/AB350-Gaming%203-Rev10-SSBB_LED.jpg
Asrock B350 K4 2.5V 820 FX
5x 820 = 4,100μF
http://www.pcdvd.com.tw/showthread.php?t=1126287

It's likely the same for the Asrock B350 Pro4.
Asrock X370 Fatal1ty K4 : 6 x 821 = 4,926 uF <_-- "6ZBJ 821 2.5" black caps
ASUS X370 Prime Pro: 820 x 8 = 6,560uF <-- 5k life rating
Gigabyte K7 / Gaming 5: capacitors at CPU side are 561 , then 561 x 10 = 5,610uF <-- black caps 10K hr rating
X370 Xpower has 8x "M 71D" with 560 and 6.3V on the other line (black)
https://www.bit-tech.net/hardware/2017/04/10/msi-x370-xpower-gaming-titanium-review/1
560 x 8= 4,480uF
B350 Pro carbon: M71J 560 6.3V (black)
https://asset.msi.com/global/picture/image/feature/mb/Z270/AM4/B350GamingProCarbon//msi-b350_gaming_pro_carbon-quality-hero.jpg
560x7 = 3920uF
B350 Tomahawk: M71R 560 6.3V
https://ockd.es/review-analisis-msi-b350-tomahawk/4/
560x7 = 3920uF
B350 Mortar: 5KW12 560 6.3V
https://asset.msi.com/global/picture/image/feature/mb/Z270/AM4/B350Mortar/msi-b350m_mortar-tuning-hero.png
560x7 = 3920uF

There's 17 capacitors that read 561 on the X370 Taichi. I have no idea how many are split to SOC but if we assume that it's 12+4 VRM and use the proportional amount (12 of 16) that would be either 12 or 13 capacitors. A conservative estimate would be 12 x 561uF = 6732uF.

Biostar GT7 : 5KW50 820 3V
http://www.tweaktown.com/image.php?image=imagescdn.tweaktown.com/content/8/1/8137_20_biostar-x370gt7-motherboard-review_full.jpg
11 capacitors but likely 8 of the 11 are for CPU based on placement.
Assuming 8x 820 = 6560uF which is very respectable

CH VI Hero's picture at http://www.kitguru.net/wp-content/uploads/2017/03/P1010473.jpg suggests SOC is at the corner

I count 7x of the ones with 561 and 5x of the ones with 101. I'm not sure how the capacitors are split since it's all bunched up.
7x561 would only be 3,927 but if we include 5x101 you get 4,432uF but I don't want to give any wrong information.


Biostar X370 GTN uses 5KX07 820 3V

http://blog.livedoor.jp/wisteriear/archives/1065630332.html
http://livedoor.blogimg.jp/wisteriear/imgs/d/b/db24c971.jpg
so it is likely all 6 for the CPU , 6 x 820 =4,920μF which is very good considering it is ITX

I appreciate you taking the time - I'm sure you know more about it than I do - I'm going to have to look for 6 % somewhere....
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post #1522 of 1994
Quote:
Originally Posted by cssorkinman View Post

I appreciate you taking the time - I'm sure you know more about it than I do - I'm going to have to look for 6 % somewhere....

You could search next to the fets, at the.... OK, actually that's quite pushing it.
post #1523 of 1994
If you want to talk about inductors, find the inductor sheet.
TI NexFET inductor normalization graph


Also measured vs calculated:


http://www.ti.com/lit/an/slpa009a/slpa009a.pdf
Edited by AlphaC - 5/4/17 at 5:46pm
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post #1524 of 1994
Taichi vrm temps video.

Worst case scenario no fans.

identical voltages used as were on K7 for comparisons sake.

https://youtu.be/MZh4ofYAo20

Next victim prime pro...till my "air end user support c6h" shows up.

My cold prepped C6H board is compromised for temp comparisons due to conformal coating...
Edited by chew* - 5/4/17 at 6:23pm
post #1525 of 1994
CPU core current max = 175A , 240W CPU power? wheee.gif
Workstation stuff
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SpecViewperf 12.0.1
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CPUMotherboardGraphicsRAM
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Hard DriveHard DriveCoolingCooling
Samsung 950 Pro / 960 Evo / 960 Pro 256GB or 51... Samsung 850 Evo 1TB SSD Storage Black or black+white Twin tower air cooler or s... EK Vardar F2-140 140mm, Phanteks PH-F140SP 140m... 
CoolingOSMonitorPower
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Case
Fractal Design Define R5 Blackout edition 
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Workstation stuff
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SpecViewperf 12.0.1
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PGA 1331
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CPUMotherboardGraphicsRAM
AMD Zen SR7 octocore (Ryzen 7 1700) Overclockable AM4 motherboard X370 To be determined , AMD Vega? 2x8GB DDR4 low-profile or heatsink-less 
Hard DriveHard DriveCoolingCooling
Samsung 950 Pro / 960 Evo / 960 Pro 256GB or 51... Samsung 850 Evo 1TB SSD Storage Black or black+white Twin tower air cooler or s... EK Vardar F2-140 140mm, Phanteks PH-F140SP 140m... 
CoolingOSMonitorPower
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Case
Fractal Design Define R5 Blackout edition 
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post #1526 of 1994
Quote:
Originally Posted by AlphaC View Post

CPU core current max = 175A , 240W CPU power? wheee.gif

1.37... biggrin.gif:thumb:

@Psym4n

What do you think ?
Edited by virpz - 5/4/17 at 6:33pm
post #1527 of 1994
Quote:
Originally Posted by AlphaC View Post

CPU core current max = 175A , 240W CPU power? wheee.gif

I asked a similar question several pages back but it was buried, I have no idea where that number is coming from as if the CPU actually pulled that much power it would be more than double the TDP and the VRM on my board would be very very dead
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post #1528 of 1994
Im not stock and my chip is not good...at all...i am good at pushing it.

I do not use good chips to show what a board can do...

Fyi...on this chip i use temp monitors off. Ocp off.

It will trip both..

I also find using junk hones my skills...when a good chip lands in my hands...i perform magic with little effort
Edited by chew* - 5/4/17 at 6:37pm
post #1529 of 1994
Quote:
Originally Posted by chew* View Post

Fyi...on this chip i use temp monitors off. Ocp off.it will trip both..
ocp off llc1 @ 4GHz@ 1.5V - MSI X370 Ti thumb.gif

I want to have @Psym4n impressions.
post #1530 of 1994
Now you knpw why the gigabyte was screaming mercy...and i can push this chip more...

3990@ 1.475...god bless any am4 board with passive only cooling...
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