This thread is all about discussing the VRMs on X399 motherboards.
Info we've got so far:
VRM list @hardwareluxx: LGA TR4 Mainboard VRM Liste
Reviews with VRM info:
Your posts are so much more organized
My x299 thread looks very hard to navigate in comparison , I have to work on that later
July 30 edit:
I think that we can glean some basic info off the marketing material
Asrock "SPS" = ISL99227 product page altered to IR3555
Taichi photos up on Newegg https://www.newegg.com/Product/Product.aspx?Item=N82E16813157785
Fatal1ty Pro Gaming https://www.newegg.com/Product/Product.aspx?Item=N82E16813157784
ASUS - "The board uses the same power solution as the Rampage VI Extreme " per ASUS
on Newegg https://www.newegg.com/Product/Product.aspx?Item=N82E16813119003
* ROG Strix X399-E announced
Gigabyte supposedly will be using 8 phase IR3553 per Gamers Nexus
Gaming 7 up on Newegg https://www.newegg.com/Product/Product.aspx?Item=N82E16813145030 Warning: Spoiler! (Click to show)
Newegg photos up https://www.newegg.com/Product/Product.aspx?Item=N82E16813144079
July 30 edit: These are 180W TDP CPUs
Thanks! But handle lots of information in one post in this forum is quite hard IMO.
If there's so much information like in the X299 thread there isn't much of a chance to keep them looking organized, even this post looked ways better in the preview than now.
Zenith Extreme is my clear choice. Awesome piece of hardware
Some evidently bad design decisions on the boards so far.
Just look how far the CPU power plugs are. Wouldn't want to push the VRM on these boards. Wonder what the temperature will be on the FETs most further away from the power plug.
Why should the FETs heat up significantly more due to the distance between them and the power plugs?
The traces and landings might get a little bit hotter but that shouldn't affect the VRM FETs a lot IMHO.
Edit: Btw, is anybody able to help me out with the different VCCs for TR4? Can't find any offical stuff from AMD about that.
But MSI is using a IR35201 again so most likely it'll be SVI2-based like AM4 with one CPU VCC and one SoC VCC. On lots of boards I do also see three more buck converter phases besides those under the large heatsink and the two DRAM converters (e.g. ASUS Zenith and MSI Gaming Pro Carbon). These could be the SoC phases. Or what do you guys think?
Wonder how much the zenith extreme in dollary doo's will be
It will lead to issues under extreme scenarios.
Remember, threadripper is essentially epyc, if/when a 32-core part comes out, the power requirements under extreme overclocks will be immerse. Putting the power plugs so far is asking for trouble.
It won't cause any issues even if your CPU consumes 2x the rated TDP and if the VRM had efficiency of 80%. 450W / 12 = 37.5A.
X399 boards cannot support 4MCM EPYCs as they're only wired for four memory channels (two dies / 2MCM).
Has anyone seen the MSI X399 Gaming Pro Carbon?
The heatisinks look like they have learned from X299, although X399 probably won't have much more than say, 2.1x the power draw of a Ryzen 8 core at equal clocks.
By contrast, note the insane power draw of Skylake E versus Kaby Lake.
Of course note that to get 4.7 GHz, on X299, the 10 core has to apply 100 mV more voltage just to get the same clock.
Let's look at the new board. https://www.msi.com/Motherboard/X399-GAMING-PRO-CARBON-AC.html#productFeature-section
Note the 2 8-pin CPU power cables and the CPU heatsink. Also note that 6 pin PCIe power cable right above the first PCIe slot - that's extra power for if you run many GPUs.
Well good on MSI for learning from X299, although hopefully Threadripper will be more efficient. The tall VRM heatsink might be an issue for tower coolers, but it is clearly needed. The below image is just marketing, but I have no doubt that the heatsink is as tall as a memory DIMM:
The X370 XPower was a letdown, but this might be a worthy board. I actually like the look of this board - I'm wondering if there will be an X399 Godlike. Good on MSI though for putting what looks like a decent heatsink on.
All that is left is to follow through with a good BIOS and rapid AGESA updates.\
Fun observation: Asus is the only company that moved their socket a bit lower so that the mounting hole doesn't mean losing a phase. Unfortunately, Asus is also the company that is only giving us 8 phases.
That's the unfortunate part IMO. I think there are a lot of people, were it possible to get a 4 GHz @ 32 core OC. That would truly be "Epyc". Maybe if AMD offereed it partly gimped - 32 cores, but with 4 rather than 8 channels and still 64 rather than 128 PCie lanes.
But yeah to use all of Epyc, we would be looking at a 128 PCIe lane, 8 channel board. Tons of traces underneath.
Hmm ... assuming 10 phases @ 60A per phase, that should be adequate. 840W, assuming 1.4V for Threadripper.
@The Stilt, is there any reason to doubt that the 16 core TR won't be more than say, 2.1x that of 8 core Ryzen,if both are at the same clock? It's just 2 Zeppelin dies and the IO. Certainly it won't be as crazy as that 7900X. I have serious doubts about how far the 18 core Intel will go. Sure it is still the "money not object" CPU, but it's got limits too.
What we really need is a 24 phase XL ATX board. 24x Fairchild FDMF5823DC 55A or 24x Intersil ISL99227 60A should do the job. Pair with a 60A choke in both cases.
Half the mosfets are underneath the board. That would in theory leave us with 1320A for the 55A and 1440A for the 60A Mosfet.
With such a big socket and 8 DIMM slots, board space is at a premium. We may need 12 or more PCB layers too.
The end result is a board that is 2 PCIe slots longer. Another MSI example - the Z87 XPower:
I'm wondering if 345.4mm x 330 mm (same as eATX) might be needed for the boards that need extra room. Certainly, it would offer the opportunity for more DIMMs - if Epyc were released on 1 socket, we'd want 16 DIMMs.
Maybe we'd also want 2 PCIe 8 pin set aside for CPU power as well. So 2 CPU power + 2 PCIe power connectors to CPU.
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