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Memory problems

Use this information to solve memory problems.

  • Follow the suggested actions in the order in which they are listed in the Action column until the problem is solved.
  • See Parts listing, Lenovo System x3550 M3 Type 4254 and 7944 to determine which components are customer replaceable units (CRU) and which components are field replaceable units (FRU).
  • If an action step is preceded by (Trained service technician only), that step must be performed only by a Trained service technician.
  • For additional memory troubleshooting information, refer to the Troubleshooting Memory - IBM BladeCenter and System x document at Troubleshooting Memory - IBM BladeCenter and System x.
  • Go to the IBM support website at Lenovo Data Center Support to check for technical information, hints, tips, and new device drivers or to submit a request for information.
SymptomAction
The amount of system memory that is displayed is less than the amount of installed physical memory.
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:
    • No error LEDs are lit on the operator information panel.
    • No DIMM error LEDs are lit on the system board.
    • Memory mirroring does not account for the discrepancy.
    • The memory modules are seated correctly.
    • You have installed the correct type of memory.
    • If you changed the memory, you updated the memory configuration in the Setup utility.
    • 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.
    • 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:
    • If a DIMM was disabled by a systems-management interrupt (SMI), replace the DIMM.
    • 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).
  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.
Multiple rows of DIMMs in a branch are identified as failing.
Note
The highest-numbered DIMM failed disabling other DIMM(s) in the same channel.
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. Reseat the DIMMs; then, restart the server.
  2. Remove the DIMM with lit error LED and replace it with an identical known good DIMM; then, restart the server. Repeat as necessary. If the failures continue after all identified DIMMs are replaced, go to step 4.
  3. Return the removed DIMMs, one at a time, to their original connectors, restarting the server after each DIMM, until a DIMM fails. Replace each failing DIMM with an identical known good DIMM, restarting the server after each DIMM replacement. Repeat step 3 until you have tested all removed DIMMs.
  4. Replace the DIMM with lit error LED; then, restart the server. Repeat as necessary.
  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. (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.
  7. (Trained service technician only) Replace the system board.