Lenovo ThinkCentre M55e - Manual (Page 14)

The following illustration shows the locations of parts on the system board for
some computer models.
1 Microprocessor and heat sink 12 Front panel connector
2 Microprocessor fan connector 13 Front USB connectors (2)
3 Memory connector 1 14 Front audio connector
4 Memory connector 2 15 CD-IN connector
5 Diskette drive connector 16 PCI adapter connectors
6 Power connector 17 PCI Express x1 adapter connector
7 IDE connector 1 18 Battery
8 IDE connector 2 19 PCI Express x16 graphics adapter
connector
9 Power fan connector 20 System fan connector
10 SATA IDE connectors (2) 21 12v power connector
11 Clear CMOS/Recovery jumper
6 Hardware Replacement Guide