IBM 71453RU manual Memory ports Dimm connectors, Bank of DIMMs Dimm connectors

vDouble-device data correction support is only available when 16 GB x4 DRAM technology DIMMs are installed in the memory expansion module and the memory expansion module is connected to a host server.

vThe memory expansion module supports memory sparing through the host server. Memory sparing reserves memory capacity for failover in the event of a DIMM failure, and the reserved capacity is subtracted from the total available memory. Memory sparing provides less redundancy than memory mirroring does. If a predetermined threshold of correctable errors is reached, the contents of the failing DIMM are copied to the spare memory, and the failing DIMM or rank is disabled. To enable memory sparing through the Setup utility, select System Settings > Memory.

vWhen you populate DIMMs in the memory expansion module, populate the larger capacity DIMMs first; then the smaller capacity DIMMs. See Table 12 on page 85 for non-mirroring mode DIMM population sequence and Table 13 on page 86 for memory-mirroring mode DIMM population sequence.

vThe memory expansion module provides eight memory ports (memory channels) and each memory port supports up to four DIMMs. Do not mix DIMMs with x4 technology (DIMMs with DRAMs that are organized with 4 data lanes) and x8 technology (DIMMs with DRAMs that are organized with 8 data lanes) in the same memory port.

Table 10. Memory ports and DIMM connectors

Memory ports	DIMM connectors
1	1, 2, 7, and 8
2	3, 4, 5, and 6
3	9, 10, 15, and 16
4	11, 12, 13, and 14
5	17, 18, 23, and 24
6	19, 20, 21, and 22
7	25, 26, 31, and 32
8	27, 28, 29, and 30

Note: 2 GB, 4 GB, and 8 GB DIMMs are x4 technology DIMMs. 16 GB and 32 GB DIMMs are x8 technology DIMMs.

vDo not mix DIMMs with 1 Gb (gigabit) technology, 2 Gb DRAM technology, or other gigabit DRAM technologies in banks of eight DIMMs on memory ports that are on the same memory controller. This is not supported in the memory expansion module. The following table lists the DIMM connectors for each bank of eight DIMMs that are on the memory ports within the same memory controller.

Table 11. DIMM banks and connectors

Bank of DIMMs	DIMM connectors
1st bank of DIMMs	1, 2, 3, 4, 5, 6, 7, and 8
2nd bank of DIMMs	9, 10, 11, 12, 13, 14, 15, and 16
3rd bank of DIMMs	17, 18, 19, 20, 21, 22, 23, and 24
4th bank of DIMMs	25, 26, 27, 28, 29, 30, 31, and 32

vDIMMs must be installed in pairs for non-mirroring mode and in sets of four for memory-mirroring mode.

84IBM System x3850 X5 and x3950 X5 Types 7145, 7146, 7143, and 7191: Installation and User's Guide