Owners Manual

For example, 8 GB and 16 GB memory modules can be mixed.
● 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.
● Mixing of more than two memory module capacities in a system is not supported.
● Unbalanced memory configurations will result in a performance loss so always populate memory channels identically with
identical DIMMs for best performance.
● Populate six identical memory modules per processor (one DIMM per channel) at a time to maximize performance.
DIMM population update for Performance Optimized mode with quantity of 4 and 8 DIMMs per processor.
● When the DIMM quantity is 4 per processor, the population is slot 1, 2, 4, 5.
● 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 9. Memory operating modes
Memory Operating Mode Description
Optimizer Mode
The Optimizer Mode if enabled, the DRAM controllers
operate independently in the 64-bit mode and provide
optimized memory performance.
Mirror Mode 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.
Single Rank Spare Mode Single Rank Spare Mode allocates one rank per channel as a
spare. If excessive correctable errors occur in a rank or
channel, while the operating system is running, they are
moved to the spare area to prevent errors from causing an
uncorrectable failure. Requires two or more ranks to be
populated in each channel.
Multi Rank Spare Mode Multi Rank Spare Mode allocates two ranks per channel as a
spare. If excessive correctable errors occur in a rank or
channel, while the operating system is running, they are
moved to the spare area to prevent errors from causing an
uncorrectable failure. Requires three or more ranks to be
populated in each 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 24x 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. For
multi rank sparing, the multiplier changes to 1/2 (ranks/
channel).
NOTE: To use memory sparing, this feature must be
enabled in the BIOS menu of System Setup.
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