Dell OptiPlex GX280 - Manual (Page 106)

4 +12 VDC Yellow
Desktop Power Supply DC Connector Pin Assignments
DC Power Connector P1
Pin Number Signal name 18-AWG Wire
1
+3.3 VDC Orange
2 +3.3 VDC Orange
3 COM Black
4 +5 VDC Red
5 COM Black
6 Red
7 Black
8 Gray
9 Purple
10 Yellow
11 Orange
12 Blue
13 Black
14 Green