Dell OptiPlex 755 User Manual page 171

18 GND
19 GND
20 NC
21 VCC (+5V)
22 VCC (+5V)
23 VCC (+5V)
24 GND
*Use 22-AWG wire instead of 18-AWG wire.
DC Power Connector P2
Pin Number Signal Name
1 GND
2 GND
3 +12 VDC
4 +12 VDC
DC Power Connectors P3
Pin Number Signal Name
1 +3.3 VDC
2 GND
3 +5 VDC
4 GND
5 +12 VDC
DC Power Connector P5
Pin Number Signal Name
1 GND
2 +5 VDC
3 NA
4 +3.3 VDC
DC Power Connector P6
Black
Black
NC
Red
Red
Red
Black
18-AWG Wire
Black
Black
Yellow
Yellow
18-AWG Wire
Orange
Black
Red
Black
Yellow
24-AWG Wire
Black
Red
NA
Orange