User's Manual

Chapter 2 Install Server Module Optional Components 17

■ Populate the DIMM slots for each memory channel that are the farthest from

the CPU first.

For example, populate D8/D5/D2 first; then D7/D4/D1 second; and finally,

D6/D3/D0. See

FIGURE 2-3.

■ Populate QR DIMMs first, followed by SR or DR DIMMs.

■ Populate QR DIMMs in blue sockets (D8/D5/D2) first then white sockets

(D7/D4/D1). See

FIGURE 2-3.

Note that QR DIMMs are supported only in white sockets if adjacent blue

socket contains a QR DIMM.

4. For maximum performance, apply the following rules:

■ The best performance is ensured by preserving symmetry. For example, adding

3x of same kind DIMMs, one per memory channel, and ensuring that both

CPUs have the same size of DIMMs populated in the same manner.

■ In certain configurations, DIMMs will run slower than their individual

maximum speed. See

TABLE 2-2 for further details.

DIMM Rank Classification Labels

DIMMs come in a variety of ranks: single, dual, or quad. Each DIMM is shipped

with a label identifying its rank classification.

TABLE 2-3 identifies the corresponding rank classification label shipped with each

DIMM.

TABLE 2-2 DIMM Speed Considerations

1 DIMMs are available in two speeds: 1066 MHz and 1333 MHz.

2 DIMM speed rules are as follows:

■ 3x DIMM per channel = 800

■ 2x DIMM per channel = 1333 MHz (for single-rank and dual-

rank DIMM or = 800 MHz (for quad-rank DIMMs)

■ 1x DIMM per channel = 1333 MHz (if using 1333 MHz

DIMMs

)

■ 1x DIMM per channel = 1066 MHz (if using 1066 MHz

DIMMs)

3 The system operates all memory only as fast as the slowest DIMM

configuration.

This DIMM configuration requires CPUs supporting 1333 MHZ.