IBM System x3550 M4 Installation And Service Manual page 257

v The RDIMM options that are available for the server are 2 GB, 4 GB, 8 GB, and
16 GB. The server supports a minimum of 2 GB and a maximum of 384 GB of
system memory using RDIMMs.
v The LRDIMM option that is available for the server is 32 GB. The server
supports a minimum of 32 GB and a maximum of 768 GB of system memory
using LRDIMMs.
Note: The amount of usable memory is reduced depending on the system
configuration. A certain amount of memory must be reserved for system
resources. To view the total amount of installed memory and the amount of
configured memory, run the Setup utility. For additional information, see
"Configuring the server" on page 102.
v A minimum of one DIMM must be installed for each microprocessor. For
example, you must install a minimum of two DIMMs if the server has two
microprocessors installed. However, to improve system performance, install a
minimum of four DIMMs for each microprocessor.
v DIMMs in the server must be the same type (RDIMM, UDIMM, or LRDIMM) to
ensure that the server will operate correctly.
v When you install one quad-rank DIMM in a channel, install it in the DIMM
connector furthest away from the microprocessor.
Notes:
1. You can install DIMMs for microprocessor 2 as soon as you install
microprocessor 2; you do not have to wait until all of the DIMM slots for
microprocessor 1 are filled.
2. DIMM slots 13-24 are reserved for microprocessor 2; thus, DIMM slots 13-24 are
enabled when microprocessor 2 is installed.
The following illustration shows the location of the DIMM connectors on the
system board.
Figure 137. DIMM connectors location
Chapter 6. Removing and replacing components
239