Dell Precision 390 - Manual (Page 21)

Quick Reference Guide
21
Back View (Tower Orientation)
1
2
3
4
1 power connector Insert the power cable into this connector.
2 voltage selection switch See the safety instructions located in the Product Information Guide for more
information.
3 back-panel connectors Plug serial, USB, and other devices into the appropriate connector.
4 card slots Access connectors for any installed PCI or PCI Express cards.