Dell EMC PowerEdge XE7440 Installation And Service Manual page 112

● Up to two LRDIMMs 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.
● 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.
NOTE: 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.
NOTE: 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.
NOTE: 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.
Mode-specific guidelines
The configurations allowed depend on the memory mode selected in the System BIOS.
Table 10. Memory operating modes
Memory Operating Mode
Optimizer Mode
Mirror Mode
Single Rank Spare Mode
Multi Rank Spare Mode
112 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.
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 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.