User`s guide

SGI
®
Altix
®
XE210 User’s Guide 29
Memory Layout
The memory controller hub (MCH) supports fully buffered DIMM (FBDIMM) in dual-
channel mode. There are a maximum of eight DIMMs in each node board and DIMMs
must be populated in groups of two (a DIMM pair).
There are four DIMM pairs as follows:
• DIMM pair 1: A1 and B1
• DIMM pair 2: C1 and D1
• DIMM pair 3: A2 and B2
• DIMM pair 4: C2 and D2
A minimum of one DIMM pair must be installed. Figure 21 illustrates the minimum
population for such a configuration.
Figure 21. Minimum Population for Dual-Channel Mode with Identical
FBDIMMs
Constraints for DIMM Pairs
The DIMM pairs (A1,B1), (C1,D1), (A2,B2), and (C2,D2) must be identical with respect
to the following attributes:
• Size (1, 2, or 4 GB)
• Speed (533 or 667 MHz)
• Organization (x4- or x8-bit)
The DIMM pairs (A1,A2), (B1,B2), (C1,C2), and (D1,D2) do not need to be identical
with respect to size, speed, and organization. The MCH will adjust to the lowest-speed
DIMM.
DIMM A2
DIMM A1
DIMM C2
DIMM C1
DIMM D2
DIMM D1
DIMM B2
DIMM B1
Channel A
Channel B
Channel C Channel D
Branch 0
Branch 1
Memory Controller Hub (MCH)