•
Up to two LRDIMMs 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 dual-processor systems, sockets A1 to A12 and sockets B1 to B12
are available. For quad-processor systems, sockets A1 to A12, B1 to B12, C1 to C12, and sockets D1 to D12 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.
•
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 39. Memory sparing
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 based on
if it is 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 of the installed memory is
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Installing and removing system components
