Lenovo THINKSERVER 3821 - Manual (Page 76)

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 8, “Parts Listing, TD200x Machine Types 3719, 3821, 3822, and 3823,” on page 237 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 event log for DIMM error messages:
v If a DIMM was disabled by a system-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 90).
4. Make sure that there is no memory mismatch when the server is at the
minimum memory configuration (two 512 MB DIMMs; see the information about
the minimum required configuration on page “Solving undetermined problems”
on page 124).
5. Add one pair of DIMMs at a time, making sure that the DIMMs in each pair are
matching.
6. Reseat the DIMMs.
7. Replace the components in step 6, one at a time, in the order shown, restarting
the server each time.
Multiple rows of DIMMs in a
branch are identified as failing. 1. Reseat the DIMMs; then, restart the server.
2. Replace the lowest-numbered DIMMs with identical known good DIMMs; then,
restart the server. Repeat as necessary. If the failures continue after all
identified pairs are replaced, go to step4.
3. Return the removed DIMMs, one pair at a time, to their original connectors,
restarting the server after each pair, until a pair fails. Replace each DIMM in the
failed pair with an identical known good DIMM, restarting the server after you
reinstall each DIMM. Replace the failed DIMM. Repeat step 3 until you have
tested all removed DIMMs.
4. (Trained service technician only) Replace the system board.
68 ThinkServer TD200x Types 3719, 3821, 3822, and 3823: Hardware Maintenance Manual