Fujitsu PRIMERGY RX2540 M7 Upgrade And Maintenance Manual page 336

Main memory
Figure 197: Mixing of DIMM within an iMC - 3DS RDIMM
General memory population rules for 2DPC configuration
– All DIMMs must be DDR5 DIMMs modules.
– All DIMMs in a channel in across of a CPU socket must have the same
number of ranks (unless explicitly specified otherwise).
– All DDR5 DIMMs must be in the same speed per CPU socket.
– Mixing of x8 DIMMs and x4 DIMMS is not allowed in the same channel or
the same CPU socket.
– Mixing of non-3DS RDIMMs and 3DS RDIMMs is not allowed in platform.
– Mixing of 9x4 RDIMMs with other DIMMs is not allowed in platform.
– Rank mixing is not allowed on a channel except for 1 Rank + 2 Rank
combination (non 3DS) or 4 Rank + 8 Rank combination(3DS), when all 16
DIMMs for a CPU socket are populated.
– Mixing vendors in a system for RDIMMs and 3DS RDIMMs is allowed.
– DIMMs with different frequencies can be mixed in the system, but lowest
frequency determines the system memory speed.
– There should be at least one DDR5 DIMM per CPU socket.
– If only one DIMM is populated in a channel, then populate it in the slot
furthest away from CPU (i.e. the black slot).
336 Upgrade and Maintenance Manual RX2540 M7