Dell OptiPlex 320 - Manual (Page 79)

System Board Components
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 floppy drive 4 system board
2 CD/DVD drive 5 heat sink assembly
3 power supply 6 hard drive
1 fan connector (FAN) 10 internal buzzer (SPKR1)
2 processor connector (CPU) 11 password jumper (PSWD)
3 processor power connector (12VPOWER) 12 RTC reset jumper (RTCRST)
4 front-panel connector (FNT_PANEL) 13 battery socket (BATT)
5 memory module connectors (DIMM_1, DIMM_2) 14 PCI Express x16 card connector