Owners Manual

Memory Operating Mode Description
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 sixteen 16 GB
dual-rank memory modules, the available system memory: 16 GB x
16(memory modules) - 8GB(1 rank sparing/channel) x 12(channel)
= 256 GB - 96 GB = 160 GB
For multi rank sparing, in a dual-processor configuration with
sixteen 64 GB quad-rank memory modules, the available system
memory: 64 GB x 16(memory modules) - 32 GB(2 rank sparing/
channel) x 12 (channel) = 1024 GB - 384 GB = 640 GB
NOTE: To use memory sparing, this feature must be
enabled in the BIOS menu of System Setup.
NOTE: Memory sparing does not offer protection against
a multi-bit uncorrectable error.
Dell Fault Resilient Mode The Dell Fault Resilient Mode if enabled, the BIOS creates an
area of memory that is fault resilient. This mode can be used by an
OS that supports the feature to load critical applications or enables
the OS kernel to maximize system availability.
Optimizer 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.
• Dual processor: Populate the slots in round robin sequence starting with processor 1.
NOTE:
Processor 1 and processor 2 population should match.
Table 35. Memory population rules
Processor Configuration Memory population Memory population information
Single processor Optimizer (Independent channel)
population order
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
• Populate in this order, odd amount
allowed.
• Odd number of DIMM population
is allowed.
NOTE: Odd number of
DIMMs will result in
unbalanced memory
configurations, which in
turn will result in
performance loss. It is
recommended to populate
all memory channels
80 Installing and removing system components