●
Populate all sockets with white release tabs first, and then black.
●
Populate the sockets by highest capacity DIMM in the following order - first in sockets with white release levers and then
black. For example, if you want to mix 16 GB and 8 GB DIMMs, populate 16 GB DIMMs in the sockets with white release tabs
and 8 GB DIMMs in the sockets with black release tabs.
●
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.
●
Memory modules of different sizes can be mixed provided that other memory population rules are followed (for example, 4
GB and 8 GB memory modules can be mixed).
●
Depending on mode-specific guidelines, populate four DIMMs per processor (one DIMM per channel) at a time to maximize
performance. For more information, see the Mode-specific guidelines section.
Table 32. Heat sink — processor configurations
Processor
Configuration
Processor Type (in
Watts)
Heat
Sink
Width
Number of DIMMs
Maximum System
Capacity
Reliability, Availability, and
Serviceability (RAS) Features
Single processor
105 W, 120 W or 135 W
68 mm
8
8
Dual processor
105 W, 120 W or 135 W
68 mm
12
12
Mode-specific guidelines
Four memory channels are allocated to each processor. The allowable configurations depend on the memory mode selected.
Advanced Error Correction Code
Advanced Error Correction Code (ECC) mode extends SDDC from x4 DRAM based DIMMs to both x4 and x8 DRAMs. This
protects against single DRAM chip failures during normal operation.
The installation guidelines for memory modules are as follows:
●
Memory modules must be identical in size, speed, and technology.
●
DIMMs installed in memory sockets with white release levers must be identical and the same rule applies for sockets with
black release levers. This ensures that identical DIMMs are installed in matched pair —for example, A1 with A2, A3 with A4,
A5 with A6, and so on.
Memory optimized independent channel 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.
Memory sparing
NOTE:
To use memory sparing, this feature must be enabled in System Setup.
In this mode, one rank per channel is reserved as a spare. If persistent correctable errors are detected on a rank, the data from
this rank is copied to the spare rank, and the failed rank is disabled.
With 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 4 GB single-rank memory modules, the available system memory is: 3/4
(ranks/channel) × 16 (memory modules) × 4 GB = 48 GB, and not 16 (memory modules) × 4 GB = 64 GB.
NOTE:
Memory sparing does not offer protection against a multi-bit uncorrectable error.
NOTE:
Both Advanced ECC/Lockstep and Optimizer modes support memory sparing.
Installing and removing system components
109
