Lenovo x3550 M4 Installation And Service Manual page 252

You can enable rank sparing memory in the Setup utility, select System Settings >
Memory. For more information, see "Using the Setup utility" on page 102.
The maximum available memory is reduced when memory rank sparing mode is
enabled.
The following diagram lists the DIMM connectors on each memory channel.
Figure 139. Connectors on each memory channel
Follow the installation sequence for rank sparing mode:
v Install at least one quad-rank DIMM in a channel.
v Install at least two single-rank or dual-rank DIMMs in a channel.
Replacing a memory module:
Use this information to install a memory module.
About this task
To install a memory module, complete the following steps:
Procedure
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System x3550 M4 Type 7914: Installation and Service Guide
Table 23. Memory rank sparing mode DIMM population sequence
Number of DIMMs
First pair of DIMMs
Second pair of DIMMs
Third pair of DIMMs
Fourth pair of DIMMs
Fifth pair of DIMMs
Sixth pair of DIMMs
Seventh pair of DIMMs
Eighth pair of DIMMs
Ninth pair of DIMMs
Tenth pair of DIMMs
Eleventh pair of DIMMs
Twelfth pair of DIMMs
Table note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory rank
sparing mode when UDIMMs are installed in the server.
1. Read the safety information that begins on "Safety" on page vii and
"Installation guidelines" on page 33.
Number of installed
microprocessor
1
1
1
1
1
1
2
2
2
2
2
2
DIMM connector
1, 2
4, 5
8, 9
11, 12
7, 10
3, 6
13, 14
16, 17
20, 21
23, 24
19, 22
15, 18