Dell OptiPlex 980 (Early 2010) - Manual (Page 6)

Mini-tower one full-height card
Desktop without riser card— one low-profile card
with riser card— one full-height card
Small form factor one low-profile card
PCI Express x1
Mini-tower one wireless card
Desktop one wireless card
Small form factor one wireless card
Drives
Externally accessible - 5.25-inch drive bay(s)
Mini-tower two bays
Desktop one bay
Small form factor one slimline bay
Externally accessible - 3.5-inch drive bay (s)
Mini-tower one bay
Desktop one bay
Small form factor one bay
Internally accessible - 3.5 inch drive bay(s) for hard drives
Mini-tower two bays
Desktop one bay
Small form factor one bay
NOTE: Your computer can support up to two 2.5 inch hard drives with brackets.
External Connectors
Audio
Back panel two connectors for line-in/ microphone
and line-out
Front panel two front-panel connectors for
headphones and microphone
eSATA one 7-pin connector
Network one RJ45 connector
Parallel one 25-pin connector (bidirectional)
Serial one 9-pin connector; 16550C-compatible
USB - Front panel
Mini-tower four connectors
Desktop two connectors
Small form factor two connectors
USB - Back panel
Mini-tower six connectors
Desktop six connectors
Small form factor six connectors