HP ProLiant BL680c G7 Server-Blade - Manual (Page 48)

Hardware options installation 48
DIMMs save up to 15 to 20 percent per DIMM compared to using the standard 1.5V DIMMs. This savings
is made possible by the Model 7510 Intel® SMB included on the HP ProLiant BL680c G7 Server Blade model
that supports the Intel® Xeon® E7 family processors. LV DIMMs are not supported on the HP ProLiant BL680c
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 Definition
1 Size —
2 Rank 1R = Single-rank
2R = Dual-rank
4R = Quad-rank
3 Data width x4 = 4-bit
x8 = 8-bit
4 Voltage rating L = Low voltage (1.35v)
Blank or omitted = Standard