IBM 8688 manual Disk drives, Remove PCI adapters, and see if the problem remains, Midplane VRM

Service Processor message	FRU/action
12V H Bus Fault	1.	Disk drives
	2.	Disk drive backplane
	3.	I/O board
	4.	Power backplane
	5.	Power cables
	6.	Midplane board
5V Fault	1.	Remove PCI adapters, and see if the problem remains.
	2.	I/O board.
Cable: Control Panel Not Present	Cable to Light Path panel
Cable: SCSI I2C cable not detected	Cable to SCSI backplane
Cable: Service Processor Not Present	1.	Remote Supervisor Adapter
	2.	I/O board
Center Card Power Fault	1.	Midplane VRM
	2.	Midplane board
CPU 1-4 Over Temperature	1.	Check airflow blockage
	2.	Check fans
	3.	Microprocessor 1-4
Failure reading I2C device. Check devices on	1.	Restart the server
bus x.
	2.	I/O board
Fan 1-4 Failure	1.	Check fan connection.
	2.	Fan.
Fan 1-4 not detected	1.	Check fan connection.
	2.	Fan.
Fan 1-4 Outside Recommended Speed	1.	Check fan connection.
	2.	Fan.
Invalid Fan configuration	1.	Check fan connections.
	2.	Fans.
Hard Drive 1-2 Fault	Run diagnostics.
Hard Drive 1-2 removal detected	1.	Hard disk drive
	2.	Run diagnostics
Integrated Systems Management Processor	1.	Remove ac power for 20 seconds, reconnect and reboot,
encountered failures upon starting
		and run diagnostics.
	2.	I/O board.
Invalid CPU configuration	Ensure microprocessor 1 is properly installed.
CPU Card Machine Check TOR_MCK	1.	Run diagnostics.
	2.	Microprocessors.
	3.	Processor board.
	4.	Memory board.
	5.	I/O board.
	6.	Midplane board.

156IBM xSeries 450 Type 8688: Hardware Maintenance Manual and Troubleshooting Guide