Hardware options installation  51 
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 
3R = Three-rank 
4R = Quad-rank 
3 
Data width  x4 = 4-bit 
x8 = 8-bit 
4 
Voltage rating  L = Low voltage (1.35V) 
U = Ultra low voltage (1.25V) 
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 more information about product features, specifications, options, configurations, and compatibility, see 
the product QuickSpecs on the HP Product Bulletin website (http://www.hp.com/go/productbulletin). 
 
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.