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DIMM identification
To determine DIMM characteristics, use the label attached to the DIMM and the following illustration and
table.
Item Aspect 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 (1.35 V)
U = Ultra low voltage (1.25 V)
Blank or omitted = Standard
5
Memory speed 12800 = 1600 MT/s
10600 = 1333 MT/s
8500 = 1066 MT/s
6
DIMM type R = RDIMM (registered)
E = UDIMM (unbuffered with ECC)
L = LRDIMM (load reduced)
For the latest supported memory information, see the QuickSpecs on the HP website (http://www.hp.com).
Single-rank and dual-rank DIMMs
DIMM configuration requirements are based on these classifications:
• Single-rank DIMM—One set of memory chips that is accessed while writing to or reading from the
memory.
• Dual-rank DIMM—Two single-rank DIMMs on the same module, with only one rank accessible at a time.
The server memory control subsystem selects the proper rank within the DIMM when writing to or reading
from the DIMM.