DIMM Types RDIMM LRDIMM 3DS RDIMM Optane
PMem
module
RDIMM allowed not allowed not allowed allowed
LRDIMM not allowed allowed not allowed allowed
3DS RDIMM not allowed not allowed allowed allowed
Optane
PMem
module
allowed allowed allowed not allowed
Table 3: Mixing of DIMM types within a channel
10.2.3 Modes of operation
10.2.3.1
DDR4 DIMM
–
Unbalanced configurations can lead to significantly reduced bandwidth
because the system will fracture the memory space into multiple regions
–
If two DIMMs with different capacity are installed in one channel, the one
with higher capacity has to be placed in slot 1 of a channel. E.g. 1A, 1B, …
–
Rank sparing mode is not supported.
Normal mode
–
Normal mode requires 1, 4, 6 or 12 memory modules per CPU.
–
ADDDC Sparing is available in case system configured by DDR4 xRx4
DIMM only.
–
All channels must run at the same interface frequency but individual
channels may run at different DIMM timings (RAS latency, CAS latency, and
so forth).
Main memory
240 Upgrade and Maintenance Manual RX4770 M6
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