IBM 390, 387, 393, 391 Memory module installation rules, Udimm, DIMMA1, DIMMA2, DIMMB1, DIMMB2

Memory module installation rules

Your server has four memory slots for installing or replacing DDR3 UDIMMs with ECC technology.

•Supports 2 GB and 4 GB 1333 MHz DDR3 UDIMMs

•Single-rank or dual-rank

•Minimum system memory: 2 GB (only one 2 GB memory module installed in the DIMMA2 slot)

•Maximum system memory: 16 GB (one 4 GB memory module installed in each of the four memory slots)

The following illustration helps you to locate the memory slots on the system board.

Figure 36. Memory slots on the system board

	Memory slot 4 (DIMMB2)		Memory slot 2 (DIMMA2)
1		3
	Memory slot 3 (DIMMB1)		Memory slot 1 (DIMMA1)
2		4

The following table provides information about the memory module installation rules that you should consider when installing or removing a memory module. The “X” mark indicates the memory slot(s) into which the memory module(s) should be installed in different situations. The numbers 1, 2, 3, and 4 indicate the installation sequence.

Note: The installed memory modules must be the same type with the same voltage and frequency.

UDIMM	DIMMA1	DIMMA2	DIMMB1	DIMMB2
One UDIMM		X
Two UDIMMs		X, 1		X, 2
Three UDIMMs	X, 3	X, 1		X, 2
Four UDIMMs	X, 3	X, 1	X, 4	X, 2

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