Memory module installation rules and order

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

Your server has 24 memory slots with 24 channels. For a list of supported memory options, see:

Lenovo ServerProven website.

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 is shown below.

Memory modules and processors layout

Figure 1. Memory modules and processors layout
Memory module and processor location

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
Processor	Processor 2												Processor 1
UMC No.	2	1	5	0	4	3	9	10	6	11	7	8	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	F	E	D	C	B	A	G	H	I	J	K	L
DIMM No.	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1

General DIMM mixing rules

DIMMs	Coexist in a system
9x4 RDIMMs and other RDIMM types	x
3DS RDIMMs and other RDIMM types	x
128 GB 3DS RDIMMs and 256 GB 3DS RDIMMs	x
x4 RDIMMs and x8 RDIMMs	x
Different DRAM density (16Gbit, 24Gbit, and 32Gbit)^1,2,5	x (for 9004 series processors)
Different DRAM density (16Gbit, 24Gbit, and 32Gbit)^1,2,5	√ (for 9005 series processors)
RDIMMs of different capacity^3,4	√
RDIMMs of different ranks (1R and 2R)^4,5	√
RDIMMs manufactured by different vendors	√
Note The 16Gbit DRAM is used in 16 GB, 32 GB, and 64 GB RDIMMs. The 24Gbit DRAM is used in 48 GB and 96 GB RDIMMs. The 32Gbit DRAM is used in 128 GB 2Rx4 RDIMMs. Before installing 24Gbit-based RDIMMs, make sure to apply the UEFI firmware version KAE106S or later to the server first and remove all existing 16Gbit-based RDIMMs. When installing RDIMMs of different capacity, install the RDIMM of the highest capacity first following the population sequence. For optimal performance, it is recommended to install RDIMMs of identical capacity and rank in the same channel of the two processors. Mixing 1R and 2R RDIMMs or mixing RDIMMs based on different DRAM density in a system equipped with 9005 series processors may have an impact on performance. Servers with 9004 series processors do not support 6400 MHz RDIMMs.

Memory module installation order

Note

In the following tables:

S1–S24 indicate DIMM slots 1–24.
1–24 indicate the installation order.

For example, when 12 DIMMs are installed for two processors, the installation order is slot 7, 19, 6, 18, 9, 21, 4, 16, 8, 20, 5, 17.

With one processor

The following table shows the DIMM population sequence when one processor is installed.

Table 2. DIMM population sequence for one processor
Total DIMMs	Processor 1
Total DIMMs	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

With two processors

The following table shows the DIMM population sequence when two processors are installed.

Table 3. DIMM population sequence for two processors
Total DIMMs	Processor 1
Total DIMMs	S12	S11	S10	S9	S8	S7	S6	S5	S4	S3	S2	S1
2 DIMMs						1
4 DIMMs						1	3
8 DIMMs				5		1	3		7
12 DIMMs				5	9	1	3	11	7
16 DIMMs		13		5	9	1	3	11	7		15
20 DIMMs		13	17	5	9	1	3	11	7	19	15
24 DIMMs	21	13	17	5	9	1	3	11	7	19	15	23
Total DIMMs	Processor 2
Total DIMMs	S24	S23	S22	S21	S20	S19	S18	S17	S16	S15	S14	S13
2 DIMMs						2
4 DIMMs						2	4
8 DIMMs				6		2	4		8
12 DIMMs				6	10	2	4	12	8
16 DIMMs		14		6	10	2	4	12	8		16
20 DIMMs		14	18	6	10	2	4	12	8	20	16
24 DIMMs	22	14	18	6	10	2	4	12	8	20	16	24

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Memory modules and processors layout​

General DIMM mixing rules​

Memory module installation order​

Memory modules and processors layout

General DIMM mixing rules

Memory module installation order