Owners Manual

● Up to two RDIMMs can be populated per channel regardless of rank count.
● A maximum of two different ranked DIMMs can be populated in a 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).
● 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.
● 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.
● 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.
● 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.
● When the DIMM quantity is 4, the population is slot 1, 2, 4, 5.
● When the DIMM quantity is 8, the population is slot 1, 2, 4, 5, 7, 8, 10, 11.
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.
Installing and removing system components 67