Memory Problems - IBM System x3550 M3 Type 4254 Problem Determination And Service Manual

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 x3550 M3 Types 4254 and 7944," on page 159 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.
v Go to the IBM support Web site at http://www.ibm.com/systems/support/ to check for technical
information, hints, tips, and new device drivers or to submit a request for information.
Symptom
The amount of system memory
that is displayed is less than the
amount of installed physical
memory.
90
IBM System x3550 M3 Types 4254 and 7944: Problem Determination and Service Guide
Action
1. Make sure that:
v No error LEDs are lit on the operator information panel.
v No DIMM error LEDs are lit on the system board.
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.
v There is no memory mismatch when the server is at the minimum memory
configuration.
2. Reseat the DIMMs, and then restart the server.
3. 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, reseat the DIMM; then, run
the Setup utility and enable the DIMM.
4. Check that all DIMMs are initialized in the Setup utility; then, run memory
diagnostics (see "Running the diagnostic programs" on page 116).
5. 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.
6. Re-enable all DIMMs using the Setup utility, and then restart the server.
7. (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.
8. (Trained service technician only) Replace the system board.