Dell OptiPlex 320 - Manual (Page 104)

DC Power Connector P2
DC Power Connectors P3 and P5
DC Power Connector P4
DC Power Connector P7
18 GND Black
19 GND Black
20 NC N/C
21 +5 VDC Red
22 +5 VDC Red
23 +5 VDC Red
24 GND Black
*Use 22-AWG wire instead of 18-AWG wire.
Pin Number Signal Name 18-AWG Wire
1 GND Black
2 GND Black
3 +12 VDC Yellow
4 +12 VDC Yellow
Pin Number Signal name 18-AWG Wire
1 +3.3 VDC Orange
2 GND Black
3 +5 VDC Red
4 GND Black
5 +12 VDC White
Pin Number Signal name 18-AWG Wire
1 N/C N/C
2 GND Black
3 GND Black
4 + 3.3 VDC Orange
5 +5 VDC Red
6 +12 VDC White