Configuring and using DDR3 memory with HP ProLiant Gen8 Servers

Introduction

This paper provides an overview of the new DDR3 memory and its use in the 2 socket HP ProLiant Gen8 servers using the

latest 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 3

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, the third-generation of DDR SDRAM technology, makes improvements in bandwidth and power consumption over

DDR2. Additional improvements in DDR3 yield up to 70% power savings versus DDR2 at the same speed, and 100%

higher bandwidth over DDR2.

DDR3 Memory Technology

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, DDR3 incorporates several key enhancements:

• Standard 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 while using up to 20% less power.

• An 8-bit prefetch buffer stores more data before it is needed than the 4-bit buffer for DDR2

• Fly-by topology (for the commands, addresses, control signals, and clocks) improves signal integrity by reducing the

number of stubs and their length. The improved signal integrity, combined with “write leveling” technology, enables

DDR3 to operate at significant faster transfer rates than previous memory generations.

• A thermal sensor integrated on the DIMM module signals the chipset to reduce memory traffic to the DIMM if its

temperature exceeds a programmable critical trip point.

DDR3 Speeds

The DDR3 specification originally defined data rates of up to 1600 Mega transfers per second (MT/s), more than twice

the rate of the fastest DDR2 memory speed (Table 2). ProLiant G6 and G7 servers support a maximum DDR3 DIMM speed

of 1333 MT/s. ProLiant Gen8 servers use the new 1600 MT/s DDR3 DIMMs as well as 1333 MT/s DIMMs.

The DDR3 specification has been extended to define additional memory speeds of 1866 MT/s and 2166 MT/s. ProLiant

Gen8 servers currently support memory speeds up to 1600 MT/s. HP engineers have designed the ProLiant Gen8

platform architecture to run at memory speeds up to 1866 MT/s once processor chipsets and DIMMs that support this

speed are available.