IBM eX5 Implementation Guide

Chapter 4. IBM System x3690 X5 131

the parallelization of workloads. When Hyper-Threading is engaged in the BIOS, for each

processor core that is physically present, the operating system addresses two. For more

information, see 2.2.2, “Hyper-Threading Technology” on page 17.

All CPU options include a heat-sink.

The x3690 X5 models include one CPU standard. All five PCIe slots are usable, even with

only one processor installed, as shown in Figure 4-8 on page 126.

The second CPU is required to access the memory in the memory mezzanine (if the memory

mezzanine is installed). The second CPU can be installed without the memory mezzanine,

but its only access to memory is through the primary CPU. For optimal performance, if two

CPUs are installed, install a memory mezzanine also.

Follow these population guidelines:

򐂰 Each CPU requires a minimum of two DIMMs to operate. If the memory mezzanine is

installed, it needs a minimum of two DIMMs installed.

򐂰 Both processors must be identical.

򐂰 Consider the X7542 processor for CPU frequency-dependent workloads, because it has

the highest core frequency of the available processor models.

򐂰 The MAX5 is supported with either one or two processors installed in the x3690 X5,

although the recommendation is to have two processors installed and memory installed in

every DIMM socket in the server to maximize performance.

򐂰 If high processing capacity is not required for your application but high memory bandwidth

is required, consider using two processors with fewer cores or a lower core frequency

rather than two processors with more cores or a higher core frequency. Having four

processors can enable all memory channels and can maximize memory bandwidth. We

describe this technique in 4.8, “Memory” on page 131.

4.8 Memory

The x3690 X5 offers up to 32 DIMM sockets that are internal to the server chassis, plus an

additional 32 DIMM sockets in the MAX5 memory expansion unit.

This section covers the following topics:

򐂰 4.8.1, “Memory DIMM options” on page 133

򐂰 4.8.2, “x3690 X5 memory population order” on page 133

򐂰 4.8.3, “MAX5 memory” on page 136

򐂰 4.8.4, “Memory balance” on page 139

򐂰 4.8.5, “Mixing DIMMs and the performance effect” on page 140

򐂰 4.8.6, “Memory mirroring” on page 141

򐂰 4.8.7, “Memory sparing” on page 143

򐂰 4.8.8, “Effect on performance of using mirroring or sparing” on page 144

Implement the memory DIMMs that are internal to the x3690 X5 chassis:

򐂰 16 DIMM sockets on the system planar

򐂰 16 DIMM sockets in an optional memory mezzanine

Tip: The memory mezzanine is referred to in the announcement letter as the memory

expansion card

. It is referred to as the memory tray, in the Installation and User’s Guide

- IBM System x3690 X5.

132 IBM eX5 Implementation Guide

The memory mezzanine is an optional component and orderable as listed in Table 4-6.

Table 4-6 x3690 X5 memory mezzanine option part number

Figure 4-13 shows the memory mezzanine and DIMMs.

Figure 4-13 Location of the memory DIMMs

With the Intel Xeon 6500 and 7500 processors, the memory controller is integrated into the

processor, as shown in the architecture block diagram in Figure 4-8 on page 126:

򐂰 Processor 0 connects directly to the memory buffers and memory DIMM sockets on the

system planar.

򐂰 Processor 1 connects directly to the memory buffers and memory in the memory

mezzanine.

If you plan to install the memory mezzanine, you are required to also install the second

processor.

The x3690 X5 uses the Intel scalable memory buffer to provide DDR3 SDRAM memory

functions. The memory buffers connect to the memory controller in each processor through

Intel Scalable Memory Interconnect links. Each memory buffer has two memory channels,

and the DIMM sockets are connected to the memory buffer with two DIMMs per memory

channel (2 DPC).

Option Feature code Description

60Y0323 9278 IBM x3690 X5 16-DIMM Internal Memory Expansion

Memory

mezzanine

Memory

mezzanine

Installing the

memory mezzanine

into the server

Memory DIMMs on the

system board