Compaq ProLiant DL980 - G7 Server Guía de usuario descargar pdf (Pagina 41)

Hardware options installation 41

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 2-GB single-rank DIMMs, a dual-rank DIMM would be 4-

GB and a quad-rank DIMM would be 8-GB.

Although only one data rank is accessed at any given time for each DIMM, optimized command and

address pipelining via various interleaving schemes enables the Intel® Xeon™ 7500-series processor

architecture to benefit from dual-rank and quad-rank DIMMs. A dual-rank DIMM performs significantly

better than its single-rank counterpart. A quad-rank DIMM provides further performance improvement even

at the same DIMM capacity.

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 Memory speed 10600 = 1333-MHz

1 2 ... 36 37 38 39 40 41 42 43 44 45 46 ... 127 128

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Compaq ProLiant DL980 - G7 Server Guía de usuario Pagina 41