IBM P 615 series, Service Manual

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Memory DIMM Locations
The memory DIMMs used in the system are located on the system backplane. Your system contains 8
memory DIMM slots. Associated with each memory DIMM slot is an LED, which is located on the edge of
the system backplane. A lit LED indicates a problem with a specific memory DIMM. For more information
on the locations of the system LEDs, go to “System LED Locations” on page 21. The following rules must
be followed when removing or installing memory DIMMs:
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Memory DIMMs must be installed in quads. However, you do not need to install four new DIMMs in a
quad when you have a memory problem. Exchange each DIMM, starting the system after each change,
until the faulty DIMM has been replaced.
Notes:
1. Memory DIMMs must be installed in quads and in the correct slots. A quad is a group of four
memory DIMMs.
2. Quads are populated in DIMM slots 1, 3, 6, 8 first, and then 2, 4, 5, 7. The only two valid slot
combinations that you can use are 1, 3, 6, and 8 and 2, 4, 5, and 7.
3. At least one quad of DIMMs must be installed on the system backplane. See the following
illustration.
4. Each memory DIMM in a quad must be the same type and size. However, both quads on the
system backplane are not required to be the same.
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The system must have at least four memory DIMMs installed (1 quad).
Chapter 1. Reference Information
17