Memory Problems - IBM System x3650 M3 4255 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, Types 4255, 7945, and 7949 server," on page 157 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 For additional memory troubleshooting information, refer to the "Troubleshooting Memory - IBM
BladeCenter and System x" document at http://www-947.ibm.com/support/entry/portal/
docdisplay?brand=5000020&lndocid=MIGR-5081319.
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.
Action
Note: Each time you install or remove a DIMM, you must disconnect the server
from the power source; then, wait 10 seconds before restarting the server.
1. Make sure that:
v No error LEDs are lit on the operator information panel.
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 (see "Installing a memory
module" on page 217).
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 event log for error message 289:
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 72).
4. Make sure that there is no memory mismatch when the server is at the
minimum memory configuration (one 1 GB DIMM in slot 3).
5. Add one pair of DIMMs at a time, making sure that the DIMMs in each pair
match. Install the DIMMs in the sequence that is described in "Installing a
memory module" on page 217.
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.
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Chapter 3. Diagnostics