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 Action
Multiple DIMMs in a channel are
identified as failing.
1. Reseat the DIMMs; then, restart the server.
2. Remove the highest-numbered DIMM of those that are identified 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 highest-numbered DIMM of those identified; 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.
Chapter 3. Diagnostics 91