Hardware options installation 46
Item Description Definition
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 the latest supported memory information, see the QuickSpecs on the HP website
(http://h18000.www1.hp.com/products/quickspecs/ProductBulletin.html). At the website, choose the
geographic region, and then locate the product by name or product category.
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.
Dual-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.
Memory subsystem architecture
The memory subsystem in this server is divided into channels. Each channel supports two DIMM slots.
Channel Population order Slot number
1
C
A
1
2
2
D
B
3
4
DIMM slots in this server are identified by number and by letter. Letters identify the population order. Slot
numbers are reported by ROM messages during boot and for error reporting. For the DIMM slot locations,
see "DIMM slot locations (on page 12)."
ECC memory
The server supports the standard ECC memory correction mode. Standard ECC can correct single-bit memory
errors and detect multibit memory errors. When multibit errors are detected, the error is signaled to the server
and causes the server to halt.