IBM 7378, Problem Determination And Service Manual

Page: 98 / 362

Memory problems
v Follow the suggested actions in the order in which they are listed in the Action column until the problem
is solved.
v
See Chapter 4, “Parts listing, System x3400 M3 Types 7378 and 7379,” on page 141 to determine which
components are customer replaceable units (CRU) and which components are field replaceable units
(FRU).
v
If an action step is preceded by “(Trained service technician only),” that step must be performed only by a
trained service technician.
Symptom Action
The amount of system memory
that is displayed is less than the
amount of installed physical
memory.
1. Make sure that:
v No error LEDs are lit on the operator information panel or on the DIMM.
v Memory mirroring does not account for the discrepancy.
v The memory modules are seated correctly.
v You have installed the correct type of memory.
v If you changed the memory, you updated the memory configuration in the
Setup utility.
v
All banks of memory are enabled. The server might have automatically
disabled a memory bank when it detected a problem, or a memory bank
might have been manually disabled.
2. Check the POST error log:
v If a DIMM was disabled by a systems-management interrupt (SMI), replace
the DIMM.
v
If a DIMM was disabled by the user or by POST, run the Setup utility and
enable the DIMM.
3. Run memory diagnostics (see “Running the diagnostic programs” on page 97).
4. Make sure that there is no memory mismatch when the server is at the
minimum memory configuration (one 1 GB DIMM); see the information about
the minimum required configuration on page “Solving undetermined problems”
on page 138).
5. Add one pair of DIMMs at a time, making sure that the DIMMs in each pair
match.
6. Reseat the DIMMs, and then restart the server.
7. Reverse the DIMMs between the channels (of the same microprocessor), and
then restart the server. If the problem is related to a DIMM, replace the failing
DIMM.
8. (Trained service technician only) Install the failing DIMM into a DIMM connector
for microprocessor 2 (if installed) to verify that the problem is not the
microprocessor or the DIMM connector.
9. (Trained service technician only) Replace the system board.
80
IBM System x3400 M3 Types 7378 and 7379: Problem Determination and Service Guide