Dell PowerEdge R940 Installation and Service Manual

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System memory guidelines

The system supports DDR4 registered DIMMs (RDIMMs), load reduced DIMMs (LRDIMMs), data center persistent memory module (PMem) and non-volatile dual in-line DIMM-Ns (NVDIMM-N). System memory holds the instructions that are executed by the processor.

The PowerEdge R940 system (without PEM) contains 24 memory sockets split into two sets of 12 sockets, one set per processor. Each 12-socket set is organized into six channels. Six memory channels are allocated to each processor. In each channel, the release tabs of the first socket are marked white, and the second socket black.

The PowerEdge R940 system (with PEM) contains 48 memory sockets split into four sets of 12 sockets, one set per processor. Each 12-socket set is organized into six channels. Six memory channels are allocated to each processor. In each channel, the release tabs of the first socket are marked white, and the second socket black.

This image shows the memory socket location. — Figure 1. Memory socket location

This image shows memory socket location on the processor expansion module. — Figure 2. Memory socket location on the processor expansion module

Memory channels are organized as follows:

Table 1. Memory channelsThis tables describes memory channels and how the channels are organized.
Processor	Channel 0	Channel 1	Channel 2	Channel 3	Channel 4	Channel 5
Processor 1	Slots A1 and A7	Slots A2 and A8	Slots A3 and A9	Slots A4 and A10	Slots A5 and A11	Slots A6 and A12
Processor 2	Slots B1 and B7	Slots B2 and B8	Slots B3 and B9	Slots B4 and B10	Slots B5 and B11	Slots B6 and B12
Processor 3	Slots C1 and C7	Slots C2 and C8	Slots C3 and C9	Slots C4 and C10	Slots C5 and C11	Slots C6 and C12
Processor 4	Slots D1 and D7	Slots D2 and D8	Slots D3 and D9	Slots D4 and D10	Slots D5 and D11	Slots D6 and D12