In dual-processor systems, all DIMM sockets can have either a DIMM or DIMM filler.
Note - In dual-processor systems, DIMM filler panels are not required in sockets that do not have DIMMs installed.
In single-processor systems, all DIMM sockets associated with processor socket P0 can have either a DIMM or DIMM filler and all DIMM sockets associated with processor socket P1 must remain empty, that is, neither DIMMs nor DIMM fillers should be installed.
Note - In single-processor systems, DIMM filler panels are not required in sockets that do not have DIMMs installed.
A single DIMM configuration is supported.
Do not populate any DIMM sockets next to an empty processor socket. Each processor contains a separate memory controller.
Each processor has four channels and can support two DIMMs per channel for a maximum of eight quad-rank (QR), dual-rank (DR), or single-rank (SR) DIMMs.
If a mix of DIMM sizes (for example, 8 GB, 16 GB, 32 GB) is being installed, then install all of the largest DIMMs first, followed next by all of the next largest, and so on until all DIMMs are installed.
Note - Each processor (P0, P1) has eight associated DIMM sockets, numbered D0, D1, D2, D3, D4, D5, D6, and D7.
When mixing DIMMs with differing number of ranks within a channel, populate the DIMMs with the higher number of ranks first.
When QR DIMMs are installed within a channel they must always be populated in the blue sockets prior to populating the white sockets.
Note - While the processor used in the server supports four modes of operation – Independent Channel Mode, Lockstep Channel Mode, Mirrored Channel Mode, and, Device Tagging Mode – the server supports the Independent Channel mode only.
DIMMs should be installed into DIMM sockets starting with P0 D0 and alternating back and forth between P0 and the matching socket on P1, first filling the blue sockets, and then the white. For an example of a configuration that follows this rule, see DIMM Population Example for Optimal System Performance.
For maximum performance, apply the following rules:
The best performance is ensured by preserving symmetry. For example: adding four of the same kind of DIMMs, one per memory channel; and, if the server has two processors, ensuring that both processors have the same size of DIMMs populated in the same manner.
For optimal performance, the memory population should be identical across both sockets. Within each socket populate QR, DR, or SR DIMMs in sets of four, one per memory channel.
Further, DIMM operational frequency, or speed, is a function of the processor speed, the maximum speed of the installed DIMMs, and the DIMM configuration. All memory installed in the system will operate at the same speed. This speed will be limited to the lowest speed determined by each one of the following factors:
Maximum memory frequency supported by processor
Maximum memory frequency supported by the installed DIMMs
Memory configuration within a channel
The table below covers the memory speed limitations associated with all the possible combinations of DIMMs within an individual memory channel.