HP ProLiant AMD-based 100-series G7 servers
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Low-voltage DDR3
Customers can take advantage of the HP low voltage (LV) DDR3 memory option. LV memory can
operate at 1.35 V, reducing power and cooling requirements. Some LV DIMM configurations can
affect performance. The difference occurs in 2 DIMM per channel (DPC) configurations with dual-rank
DIMMs. In these configurations, the memory bus runs at 1.5 V with 2 DPC at 1333 MT/s, or 1.35 V
with 2 DPC at 1066 MT/s. This results in a 20% reduction in bandwidth for the lower voltage. In all
other HP LV configurations, the LV data rate is the standard 1.5V data rate. The BIOS determines the
DIMM population from the system and the operating voltage and data rate capability from the
DIMMs. The BIOS then sets the data rate based on that information.
NOTE:
Although the bandwidth reduction from DDR3-1333 to DDR3-1066 is 20%, the
measured reduction in throughput is 10%
Single rank DIMMs configured at 1, 2, and 3 DPC; and dual rank DIMMs configured at 1 and 3 DPC
run at the 1333 MT/s data rate at both voltages.
ProLiant G6 server models with the AMD 6100-Series processor support LV memory:
PC3L-10600R—1333 1066 or 800 MT/s data rate, depending on memory configuration.
DIMM configuration guidelines
ProLiant A
MD-based 100-series G7 servers support 3 DIMMs per channel for up to 24 DDR3 DIMMs.
DDR3 DIMM speeds will vary depending on number of DIMMs per channel. Consult the server
QuickSpecs to determine DIMM speeds for given configurations. Administrators can configure
Opteron-based ProLiant 100-series G7 servers using either RDIMMs or UDIMMs but RDIMM and
UDIMM memory cannot be mixed within a single server. Low voltage DIMMs can provide up to 10%
DIMM power savings. Low and standard voltage DIMMs are compatible; systems automatically adjust
voltage based on DIMMs installed.
For detailed memory configuration rules and guidelines, please use the Online DDR3 Memory
Configuration Tool at www.hp.com/go/ddr3memory-
configurator
Memory management technologies
Memory interleaving on the AMD Opteron 6100-series processors can occur between the processor
memory banks, memory channels, and between processor nodes in a multiprocessor system. All three
memory interleaving technologies are supported on the ProLiant AMD 100-series G7 servers. These
technologies are independent of each other and can operate simultaneously.
Memory bank interleaving
When memory bank
interleaving is engaged, data is routed alternately to memory banks through the
common memory channel connecting the DIMM banks and the integrated memory controller.
However, memory bank interleaving does increase the probability that more DIMMs need to be kept
in an active state (requiring more power) since the memory controller alternates between memory
banks and therefore between DIMMs.
Memory bank interleaving is automatically enabled on a processor node under the following
conditions:
Two single-rank DIMMs per channel result in two way bank interleaving
Two dual-rank DIMMs per channel result in four way bank interleaving