Dell OptiPlex 745 - Manual (Page 177)

Inside Your Computer
System Board Components
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions located in the Product Information Guide.
CAUTION: To avoid electrical shock, always unplug your computer from the electrical outlet before removing the computer cover.
NOTICE: Be careful when opening the computer cover to ensure that you do not accidentally disconnect cables from the system board.
1 optical drive 5 system board
2 floppy drive or media card reader 6 heat-sink assembly
3 power supply 7 hard drive
4 optional chassis-intrusion switch
1 fan connector (FAN) 11 internal USB (INTERNAL_USB)
2 processor connector (CPU) 12 battery socket (BATT)