HP ProLiant DL360e Configuring and using DDR3 memory with HP ProLiant Gen8 Ser - Page 3

Introduction This paper provides an overview of the new DDR3 memory and its use in the 2 socket HP ProLiant Gen8 servers using the Iatest Intel® Xeon® E5-2600 series processor family. With the introduction of HP ProLiant Gen8 servers, DDR3 maximum operating speed is increasing and a new type of Load Reduced DIMM (LRDIMM) is being introduced. We are also introducing HP SmartMemory, which provides superior performance over 3rd party memory in certain configurations. The new 2 socket HP ProLiant Gen8 servers also feature advances in memory support. HP ProLiant Gen8 servers based on the Intel® Xeon® E5-2600 series processor-family support 4 separate memory channels per CPU and up to 24 DIMM slots- allowing larger memory configurations and improved memory performance. They also incorporate HP Advanced Memory Protection technology, which improves the prediction of critical memory error conditions. In addition to describing these improvements, this paper reviews the rules, best practices, and optimization strategies that should be used when installing DDR3 memory on HP ProLiant Gen8 servers. Overview of DDR3 memory technology Basics of DDR3 memory technology DDR3 Memory Technology DDR3, the third-generation of DDR SDRAM technology, makes improvements in bandwidth and power consumption over DDR2. Additional improvements in DDR3 yield over to 70% power savings versus DDR2 at the same speed, and 100% higher bandwidth over DDR2. DDR3 DIMMs use the same 240-pin connector as DDR2 DIMMs, but the notch key is in a different position. To increase performance and reduce power consumption of DDR3, several key enhancements were made: • DDR3 DIMMs operate at 1.5V, compared to 1.8V for DDR-2 DIMMs. DDR3 Low Voltage DIMMs operate at 1.35V. For HP ProLiant Gen8 servers, the majority of new DDR3 DIMMs are Low Voltage. These HP SmartMemory DIMMs enable the same performance as standard 1.5V DIMMs, but use up to 20% less power. • An 8-bit prefetch buffer stores more data before it is needed than the 4-bit buffer for DDR2 does. • Fly-by topology (for the commands, addresses, control signals, and clocks) improves signal integrity by reducing the number of stubs and their length. This feature requires the controller to support "write leveling" on DDR3 DIMMs. • A thermal sensor integrated on the DIMM module signals the chipset to throttle memory traffic to the DIMM if DIMM temperature exceeds a programmable critical trip point. DDR3 Speeds The DDR3 specification originally defined data rates of up to 1600 Megatransfers per second (MT/s), more than twice the rate of the fastest DDR2 memory speed (Table 2). G6 and G7 ProLiant servers supported a maximum DDR3 DIMM speed of 1333 MT/s. Gen8 ProLiant servers use the new 1600 MT/s DDR3 DIMMs as well as 1333 MT/s DIMMs. 3