Dell PowerEdge XE9685L Installation and Service Manual

The following are the recommended guidelines for installing memory modules:

• All DIMMs must be DDR5.
• DIMM mixing configurations are not supported. All DIMM slots must be populated with the exact same DIMMs.
• Populate memory module sockets only if a processor is installed.
  • A minimum of one DIMM must be populated for each installed processor.
• In Optimizer Mode, the DRAM controllers operate independently in the 64-bit mode and provide optimized memory performance.

  Table 1. Memory population rulesThe below table describes the memory population information.

  Processor	Memory population	Memory population information
  Dual processor (Start with processor1. Processor 1 and processor 2 population should match)	A{1}, B{1}, A{2}, B{2}, A{3},B{3}, A{4}, B{4}, A{5}, B{5},A{6}, B{6}, A{7}, B{7} A{8},B{8}, A{9}, B{9}, A{10},B{10}, A{11}, B{11}, A{12}, B{12},	12 DIMMs per processor are allowed.

• In a dual-processor configuration, the memory configuration for each processor must be identical. For example, if you populate socket A1 for processor 1, then populate socket B1 for processor 2, and so on.
• Populate all the sockets with white release tabs first, followed by the sockets with black release tabs.
• Unbalanced or odd memory configurations result in a performance loss, and the system may not identify the memory modules being installed. Always populate memory channels identically with equal DIMMs for the best performance.
• For best performance, populate all memory channels equally 1(2 DIMMs per CPU) using identical DIMMs.
• Mixing module types within a memory channel is not supported. All DIMMs populated must be RDIMM.
• Mixing different widths (x4 and x8) is not supported.