General Memory Module Installation Guidelines - Dell PowerEdge 1855 Installation And Troubleshooting Manual

The following procedures describe how to remove and install the following components:
Memory modules
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Daughter cards
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Microprocessors
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Server module battery
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Hard drives
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Memory
The six memory module sockets can accommodate from 512 MB to 16 GB of registered ECC PC2-3200 (DDR 2 400) memory. The memory sockets are located
near the back of the server module board. See
You can upgrade the system memory by installing combinations of 256-MB, 512-MB, 1-GB, 2-GB, or 4-GB registered low-profile memory modules. You can
purchase memory upgrade kits from Dell.
NOTICE: If you remove your original memory modules from the system during a memory upgrade, keep them separate from any new memory modules
that you may have, even if you purchased the new memory modules from Dell. Use only registered ECC DDR II memory modules.
NOTE: A single-memory module configuration is not supported, and the maximum memory configuration depends on the availability of single-rank 2-GB
memory modules.
NOTE: The memory modules must be PC2-3200 compliant.
The memory module sockets are arranged in three banks on two channels (A and B). The memory module banks are identified as follows:
Bank 1: DIMM1_A and DIMM1_B
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Bank 2: DIMM2_A and DIMM2_B
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Bank 3: DIMM3_A and DIMM3_B
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See Figure A-3 for the locations of the memory sockets and banks on the server module board.

General Memory Module Installation Guidelines

A single-memory module configuration is not supported.
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If two or more memory modules are installed, they must be installed in pairs of matched memory size, speed, and technology.
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Install memory modules in order of decreasing capacity, beginning with bank 1, then bank 2, and then bank 3.
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The system supports both single-ranked and dual-ranked memory modules.
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Memory modules marked with a 1R are single ranked and modules marked with a 2R are dual ranked.
If you install both single-ranked and dual-ranked memory modules, the dual-ranked memory modules must be installed in bank 1, regardless of
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capacity.
NOTE: Dual-rank memory modules with less capacity take precedence over single-ranked memory modules with greater capacity.
Dual-ranked memory modules are not supported in bank 3.
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Table 6-1 and Table 6-2 show examples of different memory configurations.
memory modules.
Table 6-1. Sample Memory Configurations
Total Memory DIMM1_A DIMM1_B
512 MB 256 MB 256 MB
1 GB 256 MB 256 MB
1 GB 512 MB 512 MB
2 GB 512 MB 512 MB
2 GB 1 GB 1 GB
3 GB 1 GB 1 GB
3 GB 512 MB 512 MB
4 GB 1 GB 1 GB
4 GB 1 GB 1 GB
6 GB 2 GB 2 GB
6 GB 1 GB 1 GB
8 GB 2 GB 2 GB
Figure A-3 in "Server Module Board Connectors."
DIMM2_A DIMM2_B DIMM3_A
none none none
256 MB 256 MB none
none none none
512 MB 512 MB none
none none none
512 MB 512 MB none
512 MB 512 MB 512 MB
1 GB 1 GB none
512 MB 512 MB 512 MB
1 GB 1 GB none
1 GB 1 GB 1 GB
2 GB 2 GB none
Table 6-2 lists the various allowable combinations of single- and dual-ranked
DIMM3_B
none
none
none
none
none
none
512 MB
none
512 MB
none
1 GB
none