How you use memory — and which type you use — requires an understanding of how to balance low power, capacity and performance. In this document, one in a series of Kingston Best Practice Guides for configuring memory, Kingston offers guidance and advice on how to minimize power consumption for Intel Xeon servers.
Minimizing memory power consumption can save up to 5 –10% or more of a server’s total power draw. This saving multiplies across a data center.
Fewer larger capacity memory modules reduce power consumption over a multiple of smaller capacity modules.
Speed increases power consumption — the faster the memory speed, the more power it requires compared to the same memory running at a lower speed.
Memory modules with multiple ranks (Dual Rank and Quad Rank) further reduce power consumption, as not all ranks are active at a time.
Lower power consumption leads to additional power budget headroom in a datacenter, as well as reduced cooling requirements.
Memory power management is critical when server configurations require a minimized power budget.
Today’s servers are provisioned with higher memory capacity:
- 384GB with Intel Xeon 5500/5600 series servers with 12/18 memory sockets.
- 768GB with Intel Xeon E5 series servers with 24 memory sockets
- 1.5TB with Intel Xeon E5/E5 v2 series servers with 48 memory sockets
- 3TB with Intel Xeon E5 v3 series servers with 48 memory sockets
- 2TB with Intel Xeon E7 series servers with 64 memory sockets
- 6TB with Intel Xeon E7 v2 series servers with 96 memory sockets
Xeon 5600 series support Single/Dual/Quad Rank DDR3 Registered DIMMs (RDIMMs).
Xeon E5/E5 v2 series support Single/Dual/Quad Rank DDR3 Registered DIMMs as well as DDR3 Load Reduced DIMMs (LRDIMMs)
Xeon E5 v3 series support Single/Dual Rank DDR4 Registered DIMMs as well as DDR4 Load Reduced DIMMs (LRDIMMs)
Maximum capacities available are:
- 16GB Dual Rank RDIMM (DDR3/DDR4)
- 16GB Quad Rank RDIMM (DDR3 only)
- 32GB Quad Rank RDIMM (DDR3 only)
- 32GB Quad Rank LRDIMM (DDR3/DDR4)
Use as few modules as possible by using the largest-capacity memory modules available. For example, instead of using eight 4GB modules, use four 8GB modules.
When selecting power-optimized memory configurations, determine if your application requires more capacity or more bandwidth. In balancing your performance and capacity requirements with your power budget, you can achieve the best possible balance for your servers.
Xeon E5 v3 series processors support DDR4 RDIMMs and LRDIMMs at 1.2V. DDR4 uses up to 40% less power than DDR3.
Xeon E5 v2 series processors support DDR3L-1600 memory at 1.35V. Memory running at 1600MHz at 1.35V will reduce memory power consumption by 10-15% over the same memory running at 1.5V.
Xeon E5 series servers support DDR3L-1333 at 1.35V
Quad Rank modules, such as 8GB or 16GB Quad Rank, generally provide the best power savings compared to their equivalent 8GB or 16GB Dual Rank modules — because they operate at lower speeds (1066MHz for 1DPC or 800MHz for 2DPC). Quad Rank memory will limit the available memory sockets to six per Xeon 5500/5600 series processors or eight per Xeon E5 series processors.
Mixing 1.5V and 1.35V within a system defaults the memory to 1.5V, negating potential power savings realized by using 1.35V RDIMMs.