HP BL460C G7 - Manual (Page 28)

Hardware options installation 28
• Single- and dual-rank PC3-10600 (DDR-1333) DIMMs operating at 1333 and 1066 MHz
• Quad-rank PC3-8500 (DDR-1066) DIMMs operating at 1066 MHz
Depending on the processor model, the number of DIMMs installed, and whether UDIMMs or RDIMMs are
installed, the memory clock speed may be reduced to 1066 or 800 MHz. For more information on the effect
of DIMM slot population, see "General DIMM slot population guidelines (on page 31 )."
Memory subsystem architecture
The memory subsystem in this server blade is divided into channels. Each processor supports three channels,
and each channel supports two DIMM slots, as shown in the following table.
Channel Slot Slot number
1 D
A 1
2
2 E
B
3
4
3 F
C
5
6
This multi-channel architecture provides enhanced performance in Advanced ECC mode. This architecture
also enables the Mirrored Memory and Lockstep memory modes. This server blade supports both Registered
PC3 DIMMs (RDIMMs) and Unbuffered DIMMs (UDIMMs).
DIMM slots in this server are identified by number and by letter. Letters identify the slots to populate for
specific AMP modes. Slot numbers are reported by ROM messages during boot and for error reporting.
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 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.
Low voltage DIMMs
Low Voltage DDR3 DIMMs operate at a lower voltage (1.35V) than standard voltage DDR3 DIMMs (1.5V),
and therefore consume less power. However, LVDIMMs are configured to operated at standard voltage
levels (1.5V) under the following conditions:
• If LVDIMMs are mixed with standard DDR3 DIMMs on the same server, the LVDIMMs operate at 1.5V.
• If there are two dual-rank LVDIMMs per channel on any populated memory channel in the system
running at 1333 MHz, the LVDIMMs operate at 1.5V.