IBM 88553RX, Installation Manual

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Chapter 1. Technical description
13
1.4.2 The memory-board assembly
The x455 memory-board assembly is installed in the top of the server and
mounts to the side of the midplane using two retaining levers on the top. This
location allows for easy access to all memory DIMMs without having to remove
any components from the system.
The memory-board assembly houses 28 DIMM slots. All DIMM slots can be used
with 512 MB, 1 GB or 2GB RDIMMs for a maximum of 56 GB. Memory can be
hot swapped but not hot added. This function, however, is as much a part of the
operating system as the hardware. Check with your operating system Help for
details.
Figure 1-7 The memory-board assembly, showing the two memory ports
The memory-board assembly is also equipped with LEDs for light path
diagnostics for each DIMM. In addition, the assembly is equipped with LEDs for
the following:
Power to memory port 1
Power to memory port 2
Hot-plug memory enabled
Memory used in the x455 is standard PC2100 ECC DDR SDRAM RDIMMs. The
memory is 2-way interleaved; however, 4-way interleaving is also supported
when both ports are engaged. Interleaving requires DIMMs to be installed in
matched pairs and in specific DIMM sockets (see “Memory” on page 57).
There are 14 DIMM slots in each
of the two ports, for a total of 28
DIMMs.
Memory Port 1
Memory Port 2