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Channel
3
4
For the location of the slot numbers, see "DIMM slot locations (on page 10)."
This multi-channel architecture provides enhanced performance in Advanced ECC mode.
DIMM slots in this server are identified by number and by letter. Letters identify the population order. Slot
numbers indicate the DIMM slot ID for spare replacement.
Single-, dual-, and quad-rank DIMMs
To understand and configure memory protection modes properly, an understanding of single-, dual-, and
quad-rank DIMMs is helpful. Some DIMM configuration requirements are based on these classifications.
A single-rank DIMM has one set of memory chips that is accessed while writing to or reading from the
memory. A dual-rank DIMM is similar to having two single-rank DIMMs on the same module, with only one
rank accessible at a time. A quad-rank DIMM is, effectively, two dual-rank DIMMs on the same module.
Only one rank is accessible at a time. The server memory control subsystem selects the proper rank
within the DIMM when writing to or reading from the DIMM.
Dual- and quad-rank DIMMs provide the greatest capacity with the existing memory technology. For
example, if current DRAM technology supports 8-GB single-rank DIMMs, a dual-rank DIMM would be 16
GB, and a quad-rank DIMM would be 32 GB.
LRDIMMs are labeled as quad-rank DIMMs. There are four ranks of DRAM on the DIMM, but the
LRDIMM buffer creates an abstraction that allows the DIMM to appear as a dual-rank DIMM to the
system. The LRDIMM buffer isolates the electrical loading of the DRAM from the system to allow for faster
operation. This allows higher memory operating speed compared to quad-rank RDIMMs.
DIMM identification
To determine DIMM characteristics, see the label attached to the DIMM and refer to the following
illustration and table.
Item
Description
Capacity
1
Processor 1 slot Processor 1 slot
number
C
1
G
2
D
3
H
4
Definition
8 GB
16 GB
32 GB
64 GB
Processor 2 slot Processor 2 slot
number
C
8
G
7
D
6
H
5
Hardware options installation 24
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