Undetermined Problems

1.  Power off the system.
2.  Remove or disconnect one of the following devices:
   •  Any external device or cables (including the keyboard)

3.  Switch on computer power and run diagnostic tests.
4.  If the symptom remains, repeat steps 1, 2 and 3 until you  find the failing adapter or device.
5.  If all devices are disconnected and the symptom remains, go to 'Power Systems Checkout'. If this does not solve the problem, replace the  system board.
6.  If an intermittent problem remains after replacement of the FRUs,  consider external electrical noise that can have effect on the computer.  Check that the EMC contacts on the system board are not broken. The contacts  are fragile and can be easily damaged.