Mixing memory ranks

[piranha32]

Hi!

I got to the point where I grew out of the amount of memory installed in my homelab server, and I would like to expand it. What I have right now are 2 32GB 2Rx4 memory sticks, and two empty slots.
One of friendly STHers has right now an active listing for 32GB 1Rx4 modules priced rather decently, and I would like to ask what are the disadvantages of mixing different rank modules on the same memory channel.
My setup: X11SRM-VF + W-2145

 

[RolloZ170]

afaik skylake doesn't support ( 16Gb DRAM type )32GB rank size, you need 2nd gen cascade lake.

 

[piranha32]

Thanks. So, if I understood correctly: Only 2R 32GB modules and 4R 64GB modules will work with 2145?

 

[RolloZ170]

Only 2R 32GB modules and 4R 64GB modules will work with 2145?

yes

 

[piranha32]

Thanks a lot.

And returning to the question from the topic, so future googlers will not leave disappointed: Are there any negative consequences of mixing memory ranks in one channel? Or between channels?

 

[RolloZ170]

never had the idea to do that. but mainly because i was sure it doesn't work, but it's supported.
dual ranked DIMM is better than single ranked, the IMC can do rank interleaving.
i don't think 3 rank(2R + 1R) is worse than two ranks. runs and falls with the used IMC thought.
i think the downgrade of RAM clock at 2DPC(or 3DPC) is the unwanted thing here.

 

[RolloZ170]

Thanks. So, if I understood correctly: Only 2R 32GB modules and 4R 64GB modules will work with 2145?

little addition on this because only a few people know:
the reason 1st gen doesn't support this is the 16Gb DRAM density.
this includes 32GB 1Rx4 AND also 32GB 2Rx8 (16Gb) RDIMM modules
like MEM-DR432MD-ER32 (2Rx8) 2nd gen and up
MEM-DR432LC-ER32 (2Rx4) will work with 1st gen.

 

[piranha32]

Thanks for this addition. You saved me quite time and money.