ddr4 rank interleaving

Ok, this might belong in the multiprocessing subforum, but I'll start here.
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I'm about half done building a 'bleeding edge' workstation.Dual processor Skylake-sp .

This is my new motherboard :





Supermicro X11DPi-NT. I have 2x Xeon gold 6144's paid for and on the way.
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Please look at the ram slots.
The black dimm slots are for NVRAM (not out yet ?).The blue ones are for standard registered ECC.....6 channel/cpu.
The manual starts with "2 dimms per channel is best".....ok, so that's all blue slots filled.

At this point it gets into 'rank interleaving', but for the life of me I don't understand the manual.I'm probably just reading it wrong, I'm working on it.

Normally I would always go with single rank modules, and put the same dimm in every slot, but I'm not sure that's best with this motherboard, the dual cpu thang is new to me.

The manual is here :https://www.supermicro.com/products/motherboard/Xeon/C620/X11DPi-NT.cfm

The difference between single rank and dual rank dimms is nothing cost wise, but I do want to get the order correct the first time.

I appreciate any and all advice.

Ah yes.
Took me reading that part of the manual about ten times, but I have the answer.
Best case scenario is all dimms are double rank.
It can do rank interleaving with different 'mixes' of rank....that's where it gets confusing.

Most registered dimms are dual or more, when I was shopping 8/16/32 reg ddr4 modules for X99 I think all the mainstream brand 2400 modules were dual rank (2Rx4 or 2Rx8). The only hard part was figuring out whether x4 or x8 was better (no mixing afaik) and I'm still not totally sure...one is better latency one is bandwidth but the big xeons have multiple controllers which complicates it a lot along with 1/2/3 DPC affecting speeds.

Also fuck me for not splurging for 32s (same $/GB, not load reduced) I went with 16s to "save" and now everything is double price or worse.

This motherboard actually allows mixing the bitwidth.
They should just say " Fill every slot with the best ram "
x4 should be faster , x8 has higher throughput.This I remember from when I actually overclocked...X4 single rank was what you wanted.
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There is no splurging here, I'm boned either way.
No such thing as dual rank x8 (4 Gb)in the speed I want.
My minimum ram will be 96 GB.12x 8 Gb dimms of dual rank x8.

Woop ! gotta pay if yah wanna play !