Memory module installation rules and order

Memory modules must be installed in a specific order based on the memory configuration that you implement and memory modules installed in the server.

Supported memory types

For information on the types of memory module supported by this server, see Memory section in Technical Specifications.

Information about optimizing memory performance and configuring memory is available at the Lenovo Press website:

Memory - Lenovo Press

In addition, you can take advantage of a memory configurator, which is available at the following site:

Lenovo Enterprise Solutions Configurator (Memory Configurations)

Specific information about the required installation order of memory modules in your server based on the system configuration and memory mode that you are implementing is shown below.

Your server has 12 channels, 12 memory slots, and supports:

• Minimum memory:

  • RDIMM: 16 GB using 1 x 16 GB RDIMM

• Maximum memory:

  • RDIMM: 768 GB using 12 x 64 GB RDIMMs

• Type (depending on the model):

  • TruDDR5 4800MHz RDIMM: 16 GB (1Rx8), 32 GB (2Rx8)

  • TruDDR5 4800MHz 10x4 RDIMM: 64 GB (2Rx4)

For a list of supported memory options, see Lenovo ServerProven website.

The following illustration helps you to locate the memory module slots on the system board (system board assembly).

Figure 1. Memory modules and processors layout

The memory-channel configuration table below shows the relationship between the processors, memory controllers, memory channels, and memory module slot numbers.

Table 1. Memory slot and channel identification

UMC No.	2	1	5	0	4	3	9	10	6	11	7	8
Channel No.	F	E	D	C	B	A	G	H	I	J	K	L
DIMM No.	12	11	10	9	8	7	6	5	4	3	2	1

Memory module installation guideline

Follow the rules below when installing DIMMs:

• Mixing DIMMs from different vendors is supported in a system.

• Mixing x4 and x8 DIMMs is not allowed in a system.

• Only single-rank and dual-rank DIMM mixing is allowed in a system.

• When installing DIMMs with different capacity, install the DIMM with the highest capacity first following population sequence.

• For best performance, the population recommends identical memory capacity and rank across all 12 channels.

Memory module installation order

Note

In the following tables:

• S1-S12 indicate DIMM slots 1-12.

• 1-12 indicate the installation order.

The following table shows the DIMM population sequence.

Table 2. DIMM population sequence

Total DIMMs	Slot number
	S12	S11	S10	S9	S8	S7		S6	S5	S4	S3	S2	S1
1 DIMM						1
2 DIMMs						1		2
4 DIMMs				3		1		2		4
6 DIMMs				3	5	1		2	6	4
8 DIMMs		7		3	5	1		2	6	4		8
10 DIMMs		7	9	3	5	1		2	6	4	10	8
12 DIMMs	11	7	9	3	5	1		2	6	4	10	8	12