Dell OptiPlex GX280 - Manual (Page 111)

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 +5 VDC Red
7 COM Black
8 POK Gray
9 +5 VFP Purple
10 +12 VDC Yellow
11 +3.3 VDC* Orange
12 –12 VDC Blue