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post #10 of (permalink) Old 07-30-2017, 09:10 PM
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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.

Originally Posted by The Stilt View Post

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).

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.

Originally Posted by PsyM4n View Post

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.

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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