Memory problemsv Follow the suggested actions in the order in which they are listed in the Action column until the problemis solved.v See Chapter 4, “Parts listing, System x3550 M3 Types 4254 and 7944,” on page 159 to determine whichcomponents 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 aTrained service technician.v Go to the IBM support Web site at http://www.ibm.com/systems/support/ to check for technicalinformation, hints, tips, and new device drivers or to submit a request for information.Symptom ActionThe amount of system memorythat is displayed is less than theamount of installed physicalmemory.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 theSetup utility.v All banks of memory are enabled. The server might have automaticallydisabled a memory bank when it detected a problem, or a memory bankmight have been manually disabled.v There is no memory mismatch when the server is at the minimum memoryconfiguration.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), replacethe DIMM.v If a DIMM was disabled by the user or by POST, reseat the DIMM; then, runthe Setup utility and enable the DIMM.4. Check that all DIMMs are initialized in the Setup utility; then, run memorydiagnostics (see “Running the diagnostic programs” on page 116).5. Reverse the DIMMs between the channels (of the same microprocessor), andthen restart the server. If the problem is related to a DIMM, replace the failingDIMM.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 connectorfor microprocessor 2 (if installed) to verify that the problem is not themicroprocessor or the DIMM connector.8. (Trained service technician only) Replace the system board.90 IBM System x3550 M3 Types 4254 and 7944: Problem Determination and Service Guide
