IBM 7378, Problem Determination And Service Manual

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identical in size, type, rank, and organization, but not in speed. The channels run
at the speed of the slowest DIMM in any of the channels.
v The maximum available memory is reduced to 2/3 of the installed memory when
memory sparing mode is enabled. For example, if you install 72 GB of memory
using RDIMMs, only 48 GB of addressable memory is available when you use
memory sparing.
The following table shows the installation sequence for installing DIMMs for each
microprocessor and the sparing DIMM in memory online-spare mode:
Table 14. Memory sparing mode DIMM population sequence
DIMMs
Number of installed
microprocessors
DIMM slots
1st set of DIMMs 1 3, 6, 8
2nd set of DIMMs 1 2, 5, 7
3rd set of DIMMs 2 11, 14, 16
4th set of DIMMs 2 10, 13, 15
Notes:
1. The 3rd and 4th sets of DIMMs can be installed right after microprocessor 2 is
installed even 1st and 2nd sets of DIMM slots are not full.
2. DIMM slots 1, 4, 9, and 12 are not used in memory sparing mode.
Removing a memory module
Retaining
clip
DIMM
To remove a dual inline memory module (DIMM), complete the following steps:
1. Read the safety information that begins on page vii and “Handling
static-sensitive devices” on page 151.
2. Turn off the server and peripheral devices, and disconnect the power cords
and all external cables.
3. Carefully turn the server on its side so that it is lying flat, with the cover facing
up.
Attention: Do not allow the server to fall over.
4. Unlock and remove the left-side cover (see “Removing the left-side cover” on
page 181).
5. Remove the hot-swap power supply or power supplies from the power-supply
cage (see “Removing a hot-swap power supply” on page 273).
6. Rotate the power-supply cage to its open position (see “Opening the
power-supply cage” on page 154).
7. Remove the air baffle (see “Removing the air baffle” on page 212).
8. Locate the DIMM connectors on the system board (see “System board internal
connectors” on page 15).
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IBM System x3400 M3 Types 7378 and 7379: Problem Determination and Service Guide