Specifications

Chapter 4. Product information and technology 87
򐂰 Small physical footprint
The performance of eDRAM when implemented on-chip is similar to
conventional SRAM but requires far less physical space. IBM on-chip eDRAM
uses only one-third of the components used in conventional SRAM, which
has a minimum of six transistors to implement a 1-bit memory cell.
򐂰 Low energy consumption
The on-chip eDRAM uses only 20% of the standby power of SRAM.
POWER7 processor and intelligent energy
Energy consumption is an important area of focus for the design of the POWER7
processor, which includes intelligent energy features that help to optimize energy
usage and performance dynamically, so that the best possible balance is
maintained. Intelligent energy features (such as EnergyScale) work with the IBM
Flex System Manager or IBM Systems Director Active Energy Manager™ to
optimize processor speed dynamically, based on thermal conditions and
system usage.
For more information about the POWER7 energy management features, see
Adaptive Energy Management Features of the POWER7 Processor, found at the
following website:
http://researcher.watson.ibm.com/researcher/files/us-lefurgy/hotchips22
_power7.pdf
4.6 Memory subsystem
Each POWER7 processor used in the compute nodes has an integrated memory
controller. Industry standard DDR3 Registered DIMM (RDIMM) technology is
used to increase reliability, speed, and density of memory subsystems.
4.6.1 Memory placement rules
The recommended memory minimum and maximum for each server is listed in
Table 4- 4.
Table 4-4 Recommended memory limits
Model Minimum memory Maximum memory
p260 8 GB 256 GB (16x 16 GB DIMMs)
p460 32 GB 512 GB (32x 16 GB DIMMs)