Dell Precision Tower 3420 Owner's Manual page 50

Feature
PCI Express x16 (wired as x4) data width (maximum) - four PCI Express lanes
Mini Tower
Small Form Factor
PCI Express x16 data width (maximum) - 16 PCI Express lanes
Mini Tower, Small Form Factor
Serial ATA
Mini Tower
Small Form Factor
Memory
Internal USB
Mini Tower
Small Form Factor
System fan
Front panel control
Mini Tower
Mini Tower – thermal sensor
Processor
Processor fan
Service mode jumper
Password clear jumper
RTC reset jumper
Internal speaker
Intruder connector
Power connector:
Table 30. Controls and lights
Feature
Front of the computer
Power button light
Drive activity light
Back of the computer
50
Specification
One 164-pin connector
None
One 164-pin connector
Four 7-pin connectors
Three 7-pin connectors
Four 288-pin connectors
One 20-pin connector
One 14–pin connector
One 4-pin connector
One 6–pin and two 20–pin connector
One 2-pin connector
One 1150-pin connector
One 4-pin connector
One 2-pin connector
One 2-pin connector
One 2-pin connector
One 4-pin connector
One 3-pin connector
One 8-pin. one 4-pin,
Specification
White light — Solid white light indicates power-on state;
blinking white light indicates sleep state of the computer.
White light — Blinking white light indicates that the
computer is reading data from or writing data to the hard
drive.