Dell OptiPlex 740 - Manual (Page 65)

12. Replace the computer cover (see Replacing the Computer Cover ).
13. Connect the AC power cable to the AC power connector.
DC Power Connectors
DC Power Connector P1
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 +3.3 V Orange
14 -12 V* Blue
15 GND Black
16 PWR_PS_ON Green
17 GND Black
18 GND Black
19 GND Black
20 NC N/C
21 VCC (+5V) Red
22 VCC (+5V) Red
23 VCC (+5V) Red
24 GND Black