Independent memory mode installation order

Independent memory mode provides the highest level of memory performance, but lacks failover protection. The DIMM installation order for independent memory mode varies based on the number of processors and memory modules installed in the server.

Follow the rules below when installing memory modules in independent mode:

There should be at least one DDR5 DIMM per processor.
All DDR5 memory modules must operate at the same speed in the same system.
Memory population must be identical between processors.
Memory modules from different vendors are supported.
Note
When ThinkSystem 128GB TruDDR5 4800MHz (4Rx4) 3DS RDIMM v1 and/or ThinkSystem 256GB TruDDR5 4800MHz (8Rx4) 3DS RDIMM v1 is installed in a system, no other memory module types can be installed.
In each memory channel, populate the slot farthest from the processor (slot 0) first.
All memory modules must be DDR5 memory modules.
x8 memory modules and x4 memory modules cannot be mixed in a system.
Mixing 16Gbit-based (16 GB, 32 GB, 64 GB, 128 GB, 256 GB), 24Gbit-based (96 GB), 32Gbit-based (128 GB) memory module is not allowed in a system.
96 GB memory module must be identically populated in the system.
96 GB memory module can only support 1DPC (8 DIMMs per processor) and 2DPC (16 DIMMs per processor) configurations.
All memory modules to be installed must be of the same type.
- Value RDIMM cannot be mixed with non-value RDIMMs in a system.
- 3DS RDIMM cannot be mixed with non-3DS RDIMMs in a system.
All memory modules in a system must have the same number of ranks.
When ThinkSystem 256GB TruDDR5 4800MHz (8Rx4) 3DS RDIMM v1 is installed in the system, the maximum number of supported drives is twenty-four drives.
Before installing 24Gbit-based (96 GB) or 32Gbit-based (128 GB) memory module to the system, then remove all existing 16Gbit-based (16 GB, 32 GB, 64 GB, 128 GB, 256 GB) memory modules.

With two processors

The following table shows the sequence of populating memory modules for independent mode when two processors are installed.

Table 1. Independent mode with two processors
Total DIMMs	Processor 1
Total DIMMs	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1
2 DIMMs							10
4 DIMMs¹							10							3
8 DIMMs¹			14				10			7				3
12 DIMMs¹	16		14				10			7		5		3
16 DIMMs^1,2	16		14		12		10			7		5		3		1
24 DIMMs¹	16		14	13	12		10	9	8	7		5	4	3		1
32 DIMMs^1,2	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1
Total DIMMs	Processor 2
Total DIMMs	32	31	30	29	28	27	26	25	24	23	22	21	20	19	18	17
2 DIMMs							26
4 DIMMs¹							26							19
8 DIMMs¹			30				26			23				19
12 DIMMs¹	32		30				26			23		21		19
16 DIMMs^1,2	32		30		28		26			23		21		19		17
24 DIMMs¹	32		30	29	28		26	25	24	23		21	20	19		17
32 DIMMs^1,2	32	31	30	29	28	27	26	25	24	23	22	21	20	19	18	17

Note

DIMM configurations that support the Sub NUMA Clustering (SNC) feature, which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.
DIMM configurations that support Software Guard Extensions (SGX), see Enable Software Guard Extensions (SGX) to enable this feature.

With three processors

The following table shows the sequence of populating memory modules for independent mode when three processors are installed.

Table 2. Independent mode with three processors
Total DIMMs	Processor 1
Total DIMMs	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1
3 DIMMs							10
6 DIMMs¹							10							3
12 DIMMs¹			14				10			7				3
18 DIMMs¹	16		14				10			7		5		3
24 DIMMs^1,2	16		14		12		10			7		5		3		1
36 DIMMs¹	16		14	13	12		10	9	8	7		5	4	3		1
48 DIMMs^1,2	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1
Total DIMMs	Processor 2
Total DIMMs	32	31	30	29	28	27	26	25	24	23	22	21	20	19	18	17
3 DIMMs							26
6 DIMMs¹							26							19
12 DIMMs¹			30				26			23				19
18 DIMMs¹	32		30				26			23		21		19
24 DIMMs^1,2	32		30		28		26			23		21		19		17
36 DIMMs¹	32		30	29	28		26	25	24	23		21	20	19		17
48 DIMMs^1,2	32	31	30	29	28	27	26	25	24	23	22	21	20	19	18	17
Total DIMMs	Processor 3
Total DIMMs	33	34	35	36	37	38	39	40	41	42	43	44	45	46	47	48
3 DIMMs										42
6 DIMMs¹			35							42
12 DIMMs¹			35				39			42				46
18 DIMMs¹			35		37		39			42				46		48
24 DIMMs^1,2	33		35		37		39			42		44		46		48
36 DIMMs¹	33		35	36	37		39	40	41	42		44	45	46		48
48 DIMMs^1,2	33	34	35	36	37	38	39	40	41	42	43	44	45	46	47	48

Note

DIMM configurations that support the Sub NUMA Clustering (SNC) feature, which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.
DIMM configurations that support Software Guard Extensions (SGX), see Enable Software Guard Extensions (SGX) to enable this feature.

With four processors

The following table shows the sequence of populating memory modules for independent mode when four processors are installed.

Table 3. Independent mode with four processors
Total DIMMs	Processor 1
Total DIMMs	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1
4 DIMMs							10
8 DIMMs¹							10							3
16 DIMMs¹			14				10			7				3
24 DIMMs¹	16		14				10			7		5		3
32 DIMMs^1,2	16		14		12		10			7		5		3		1
48 DIMMs¹	16		14	13	12		10	9	8	7		5	4	3		1
64 DIMMs^1,2	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1
Total DIMMs	Processor 2
Total DIMMs	32	31	30	29	28	27	26	25	24	23	22	21	20	19	18	17
4 DIMMs							26
8 DIMMs¹							26							19
16 DIMMs¹			30				26			23				19
24 DIMMs¹	32		30				26			23		21		19
32 DIMMs^1,2	32		30		28		26			23		21		19		17
48 DIMMs¹	32		30	29	28		26	25	24	23		21	20	19		17
64 DIMMs^1,2	32	31	30	29	28	27	26	25	24	23	22	21	20	19	18	17
Total DIMMs	Processor 3
Total DIMMs	33	34	35	36	37	38	39	40	41	42	43	44	45	46	47	48
4 DIMMs										42
8 DIMMs¹			35							42
16 DIMMs¹			35				39			42				46
24 DIMMs¹			35		37		39			42				46		48
32 DIMMs^1,2	33		35		37		39			42		44		46		48
48 DIMMs¹	33		35	36	37		39	40	41	42		44	45	46		48
64 DIMMs^1,2	33	34	35	36	37	38	39	40	41	42	43	44	45	46	47	48
Total DIMMs	Processor 4
Total DIMMs	49	50	51	52	53	54	55	56	57	58	59	60	61	62	63	64
4 DIMMs										58
8 DIMMs¹			51							58
16 DIMMs¹			51				55			58				62
24 DIMMs¹			51		53		55			58				62		64
32 DIMMs^1,2	49		51		53		55			58		60		62		64
48 DIMMs¹	49		51	52	53		55	56	57	58		60	61	62		64
64 DIMMs^1,2	49	50	51	52	53	54	55	56	57	58	59	60	61	62	63	64

Note

DIMM configurations that support the Sub NUMA Clustering (SNC) feature, which can be enabled via UEFI. SNC is not supported if DIMM population does not follow the sequence indicated by the table above.
DIMM configurations that support Software Guard Extensions (SGX), see Enable Software Guard Extensions (SGX) to enable this feature.

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Independent memory mode installation order

With two processors​

With three processors​

With four processors​

With two processors

With three processors

With four processors