Dell OptiPlex 960 (Late 2008) - Manual (Page 87)

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 +5 VDC Red
5 GND Black
6 +5 VDC Red
7 GND Black
8 PS_PWRGOOD Gray
9 P5AUX Purple
10 V_12P0_DIG White
11 V_12P0_DIG White
12 +3.3 VDC Orange
13 +3.3VDC/SE* Orange
14 -12 VDC Blue
15 GND Black
16 PWR_PS_ON Green
17 GND Black
18 GND Black
19 GND Black
20 NC NC
21 +5 VDC Red
22 +5 VDC Red
23 +5 VDC Red
24 GND Black
*Optional wire. Use 22-AWG wire instead of 18-AWG wire.