Dell OptiPlex 755 User Manual page 158

Pin
Number
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
158
Power Supply
Signal name 18-AWG
Wire
+5 VDC Red
GND Black
PS_PWRGOOD* Gray
P5AUX Purple
+12 VDC White
+12 VDC White
+3.3 VDC Orange
+3.3 VDC/SE Orange
+12 VDC* Blue
GND Black
PWR_PS_ON* Green
GND Black
GND Black
GND Black
NC NC
+5 VDC Red
+5 VDC Red