Owners Manual

● x4 and x8 DRAM based memory modules can be mixed. For more information, see the Mode-specific guidelines section.
● Up to two RDIMMs can be populated per channel regardless of rank count.
● If memory modules with different speeds are installed, they will operate at the speed of the slowest installed memory
module(s) or slower depending on the system DIMM configuration.
● Populate memory module sockets only if a processor is installed. For single-processor systems, sockets A1 to A12 are
available. For dual-processor systems, sockets A1 to A12 and sockets B1 to B12 are available.
● Populate all the sockets with white release tabs first, followed by the black release tabs.
● When mixing memory modules with different capacities, populate the sockets with memory modules with the highest
capacity first. For example, if you want to mix 8 GB and 16 GB memory modules, populate 16 GB memory modules in the
sockets with white release tabs and 8 GB memory modules in the sockets with black release tabs.
● In a dual-processor configuration, the memory configuration for each processor should be identical. For example, if you
populate socket A1 for processor 1, then populate socket B1 for processor 2, and so on.
● Memory modules of different capacities can be mixed provided other memory population rules are followed (for example, 8
GB and 16 GB memory modules can be mixed).
● Mixing of more than two memory module capacities in a system is not supported.
● Populate six memory modules per processor (one DIMM per channel) at a time to maximize performance.
Mode-specific guidelines
Six memory channels are allocated to each processor. The configurations allowed depend on the memory mode selected.
Memory optimized (independent channel) mode
This mode supports Single Device Data Correction (SDDC) only for memory modules that use x4 device width. It does not
impose any specific slot population requirements.
Memory sparing
NOTE: To use memory sparing, this feature must be enabled in BIOS menu of System Setup.
Table 7. Memory sparing
Memory Description
Memory sparing (Single Rank) Memory sparing allocates one rank per channel as a spare. If
excessive correctable errors occur in a rank or channel, they
are moved to the spare area while the operating system is
running to prevent errors from causing an uncorrectable
failure. Requires population of two ranks or more per channel.
Memory sparing (Multi Rank) Memory sparing allocates two ranks per channel as a spare. If
excessive correctable errors occur in a rank or channel, they
are moved to the spare area while the operating system is
running to prevent errors from causing an uncorrectable
failure. Requires population of three ranks or more per
channel.
With single rank memory sparing enabled, the system memory available to the operating system is reduced by one rank per
channel. For example, in a dual-processor configuration with twenty four 16 GB dual-rank memory modules, the available system
memory is: 3/4 (ranks/channel) × 24 (memory modules) × 16 GB = 288 GB, and not 24 (memory modules) × 16 GB = 384 GB.
This calculation changes for single rank sparing or multi rank sparing. For multi rank sparing, the multiplier changes to 1/2
(ranks/channel).
NOTE: Memory sparing does not offer protection against a multi-bit uncorrectable error.
Memory mirroring
Memory mirroring offers the strongest memory module reliability mode, providing improved uncorrectable multi-bit failure
protection. In a mirrored configuration, the total available system memory is one half of the total installed physical memory. Half
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Installing and removing system components