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64 GB LRDIMMs that are DDP (Dual Die Package) LRDIMMs must not be mixed with 128 GB LRDIMMs that are TSV (Through Silicon
Via/3DS) LRDIMMs.
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x4 and x8 DRAM based memory modules can be mixed.
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Up to two RDIMMs can be populated per channel regardless of rank count.
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Up to two LRDIMMs can be populated per channel regardless of rank count.
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A maximum of two different ranked DIMMs can be populated in a channel regardless of rank count.
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If memory modules with different speeds are installed, they will operate at the speed of the slowest installed memory module(s).
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Populate memory module sockets only if a processor is installed.
– For single-processor systems, sockets A1 to A8 are available.
– For dual-processor systems, sockets A1 to A8 and sockets B1 to B8 are available.
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Populate all the sockets with white release tabs first, followed by the black release tabs.
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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.
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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.
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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.
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Mixing of more than two memory module capacities in a system is not supported.
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Unbalanced memory configurations will result in a performance loss so always populate memory channels identically with identical
DIMMs for best performance.
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Populate six identical memory modules per processor (one DIMM per channel) at a time to maximize performance.
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To ensure proper system cooling, memory module blanks must be installed in memory sockets that are not occupied.
DIMM population update for Performance Optimized mode with quantity of 4 and 8 DIMMs per processor.
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When the DIMM quantity is 4 per processor, the population is slot 1, 2, 4, 5.
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When the DIMM quantity is 8 per processor, the population is slot 1, 2, 4, 5, 7, 8, 10, 11 (2-2-2 platforms).
Mode-specific guidelines
The configurations allowed depend on the memory mode selected in the System BIOS.
Table 25. Memory operating modes
Memory Operating Mode
Optimizer Mode
Mirror Mode
68
Installing and removing system components
Description
The Optimizer Mode if enabled, the DRAM controllers operate
independently in the 64-bit mode and provide optimized memory
performance.
The Mirror Mode if enabled, the system maintains two identical
copies of data in memory, and the total available system memory is
one half of the total installed physical memory. Half of the installed
memory is used to mirror the active memory modules. This feature
provides maximum reliability and enables the system to continue
running even during a catastrophic memory failure by switching
over to the mirrored copy. The installation guidelines to enable
Mirror Mode require that the memory modules be identical in size,
speed, and technology, and they must be populated in sets of 6 per
processor.
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