MP 7,1 Does 2019 Mac Pro support 6 x 64 GB RDIMM?

[Theophilos]

Hello,

After waiting and saving for years, I ordered a 16 core Mac Pro with the stock 32 GB RAM so I can upgrade it myself. I know the Mac Pro supports either RDIMM or LR-DIMM, but not a mix of both. I also know that Apple ships 384 GB RAM with LR-DIMM and anything below with RDIMM. I was just reading a blog at OWC and it vaguely implied that the Mac Pro doesn’t support 64 or 128 GB RDIMM. Does anyone know if this is true? Also, if it is supported, is there a performance hit from using 6 x 64 GB RDIMM as opposed to LR-DIMM?

thanks!

 

[Theophilos]

No one knows?

 

[AidenShaw]

No one knows?

What's description (part number) of the 64GiB RDIMMs you are looking at?

 

[Theophilos]

It would be 6 of these:

SuperMicro (M393A8G40MB2-CVF) 64GB 288-Pin DDR4 SDRAM ECC Registered DDR4 2933 (PC4 23400) Server Memory Model MEM-DR464L-SL01-ER29 - Newegg.com

Buy SuperMicro (M393A8G40MB2-CVF) 64GB 288-Pin DDR4 SDRAM ECC Registered DDR4 2933 (PC4 23400) Server Memory Model MEM-DR464L-SL01-ER29 with fast shipping and top-rated customer service. Once you know, you Newegg!

www.newegg.com

 

[AidenShaw]

It would be 6 of these:

SuperMicro (M393A8G40MB2-CVF) 64GB 288-Pin DDR4 SDRAM ECC Registered DDR4 2933 (PC4 23400) Server Memory Model MEM-DR464L-SL01-ER29 - Newegg.com

Buy SuperMicro (M393A8G40MB2-CVF) 64GB 288-Pin DDR4 SDRAM ECC Registered DDR4 2933 (PC4 23400) Server Memory Model MEM-DR464L-SL01-ER29 with fast shipping and top-rated customer service. Once you know, you Newegg!

www.newegg.com

I suppose that "buy a dozen and tell us if they work" isn't the answer you want. I'm not sure that there's a better answer, though.

 

[majus]

Hello,
... I was just reading a blog at OWC and it vaguely implied that the Mac Pro doesn’t support 64 or 128 GB RDIMM. Does anyone know if this is true? Also, if it is supported, is there a performance hit from using 6 x 64 GB RDIMM as opposed to LR-DIMM?

64GB RDIMMs should work fine with the Mac Pro. Performance should be about 5% better and use less energy than LRDIMMs.

One thing you have to keep in mind is that if you might ever want to go above 768GB you would have to start over with all LRDIMMs unless someone begins manufacturing compatible 128GB RDIMMs. That is likely the reason for Apple's current configuration scheme.

 

[Theophilos]

64GB RDIMMs should work fine with the Mac Pro. Performance should be about 5% better and use less energy than LRDIMMs.

One thing you have to keep in mind is that if you might ever want to go above 768GB you would have to start over with all LRDIMMs unless someone begins manufacturing compatible 128GB RDIMMs. That is likely the reason for Apple's current configuration scheme.

Thanks so much for your helpful response.

 

[bxs]

6x 64GB R-DIMMs will work fine in RAM slots 1, 3, 5, 8, 10 ands 12, and will use memory channel pairs 1, 2 and 3 out of the total of 6 memory channel pairs available. According to the LenovoPress this will provide you with 97% of the memory performance. Using all 12 RAM slots with same size DIMMs would provide 100%.