Dual- And Quad-Rank Dimms; Dimm Identification - HP ProLiant BL620c G7 User Manual

supports the Intel Xeon E7 family processors. LV DIMMs are not supported on the HP ProLiant BL620c G7
Server Blade that uses the Intel Xeon 6500 and 7500 series processors.

Dual- and quad-rank DIMMs

To understand and configure memory protection modes properly, an understanding of 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 blade 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 2-GB single-rank DIMMs, a dual-rank DIMM would be 4-GB,
and a quad-rank DIMM would be 8-GB.

DIMM identification

To determine DIMM characteristics, use the label attached to the DIMM and the following illustration and
table.
Item Description
Size
1
Rank
2
Data width
3
Voltage rating
4
Memory speed
5
Definition
—
1R = Single-rank
2R = Dual-rank
4R = Quad-rank
x4 = 4-bit
x8 = 8-bit
L = Low voltage (1.35v)
Blank or omitted = Standard
10600 = 1333-MHz
8500 = 1066-MHz
Hardware options installation 37