Central Electronics Complex; Section 2.4, "Central Electronics Complex - IBM p5 590 System Handbook

p5-590/p5-595 servers with one processor book must have a minimum of two
memory cards installed.
Each 8-way MCM (two per processor book) should have memory installed.
The same amount of memory should be used for each MCM (two per
processor book) in the system.
No more than two different sizes of memory cards should be used in any
processor book.
All MCMs (two per processor book) in the system should have the same total
memory size.
A minimum of half of the available memory slots in the system should contain
memory.
It is better to install more cards of smaller capacity than fewer cards of larger
capacity.
For high-performance computing the following in strongly recommended.
DDR2 memory is recommended for memory intensive applications.
Install some memory in support of each 8-way MCM (two MCMs per
processor book).
Use the same size memory cards across all MCMs and processor books in
the system.

2.4 Central electronics complex

The Central Electronics Complex is an 18 EIA unit drawer that houses the
processors and memory cards of the p5-590 and p5-595 systems. The
fundamental differences between p5-590 and p5-595 systems are outlined in
1.3, "General overview and characteristics" on page 4.
The CEC contains the following components:
CEC backplane that serves as the system component mounting unit
Multichip modules books that contains the POWER5 processors and L3
cache modules
Memory cards
Service processor unit
I/O books that provide the Remote I/O (RIO) ports
Fans and blowers for CEC cooling
IBM Eserver p5 590 and 595 System Handbook
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