Dell OptiPlex 755 - Manual (Page 170)

12. Replace the floppy drive or media card reader (see Installing a Floppy Drive ).
13. Replace the optical drive (see Installing an Optical Drive ).
14. Replace the computer cover (see Replacing the Computer Cover ).
15. Connect the AC power cable to the power supply AC power connector.
16. Connect your computer and devices to electrical outlets, and turn them on.
DC Power Connectors
DC Power Connector P1
NOTICE: To connect a network cable, plug the cable into the network wall jack and then plug it into the computer.
NOTE: The power supply installed in your computer is one of two options as illustrated below.
Pin Number Signal Name 18-AWG Wire
1 +3.3 VDC Orange
2 +3.3 VDC Orange
3 GND Black
4 VCC (+5 V) Red
5 GND Black
6 VCC (+5 V) Red
7 GND Black
8 PS_PWRGOOD* Gray
9 P5AUX Purple
10 V_12P0_DIG Yellow
11 V_12P0_DIG Yellow
12 +3.3 V Orange
13
(optional) +3.3V Orange
14 -12 V* Blue
15 GND Black
16 PWR_PS_ON Green
17 GND Black