IBM xSeries 330 - Manual (Page 107)

Chapter 7. Symptom-to-FRU index 99
4) Power-on system. If problem remains, suspect the following FRUs in the
order listed:
a) Power supply
b) System board
If problem goes away, replace removed items one at a time until failing
item is found (power-on and reconfigure system each time).
Notes:
1. If the problem goes away when you remove an adapter from the system, and
replacing that adapter does not correct the problem, suspect the System Board.
2. If you suspect a networking problem and all the system tests pass, suspect a
network cabling problem external to the system.