Memory Cisco UCS C240 M4

[terry-acocks]

I need to upgrade a Cisco UCS C240 M4 to 512G of memory, I Have 8 sticks of 64G 2933, will it work and just clock the memory down to 2133?

[marce1000]

  - FYI : https://memory.net/product-category/cisco/ucs/c240-m4/
            >...Do not mix DIMM LRDIMM and RDIMM types.
                If mixing memory speeds, all 24 DIMMs run at the lowest DDR4-2133 bus frequency.

  M.

[terry-acocks]

64G DDR4 RDIMMS will not work in a UCS C240 M4, am I reading this correctly? only 32G and 64G LRDIMMS will work in this server according to the link provided above. I guess it just will not recognize the 64G DDR4 RDIMMS because of the DRAM modules and the motherboard memory controller? Just making sure I don't want to waste time trying it if it will not work. This was memory we had on hand to try to upgrade server. In order to do it I have to bring the server down in a maintenance window. 

[marce1000]

  - I can't confirm , because I can't find in the page data leading to your conclusions , 

 M.

[Steven Tardy]

In general faster DDR4 DIMMs will clock slower to match CPU/platform requirements.
Not a 100% compatibility rule, but commonly what happens.

64G DDR4 LRDIMMs are validated on the C240 M4 spec sheet.
64G DDR4 RDIMMs are NOT validated. Will 64G DDR4 RDIMMs work? Unknown.
The spec sheet has a lot of good information on what will work and some known incompatible combinations, but does NOT list all of the potential combinations which won't work.

This is dependent on the exact DIMM specifications of the new DIMMs(LRDIMM or RDIMM) and currently populated exact DIMM specifications(LRDIMM or RDIMM or TSV-RDIMM).