Dell OptiPlex 390 (Mid 2011) - Manual (Page 91)

Cards
PCI Express x1
Mini-Tower up to three full-height cards
Desktop up to three low-profile cards
Small Form Factor up to one low-profile cards
PCI-Express x16
Mini-Tower up to one full-height cards
Desktop up to one low-profile cards
Small Form Factor up to one low-profile cards
Drives
Externally Accessible (5.25–inch drive bays)
Mini-Tower two
Desktop one
Small Form Factor one slim optical drive bay
Internally Accessible:
3.5–inch SATA drive bays
Mini-Tower two
Desktop one
Small Form Factor one
External Connectors
Audio:
Back Panel
Mini-Tower/Desktop three connectors once each for
line-out, line-in, and microphone
Small Form Factor two connectors for line-out and
line-in/microphone
Front Panel two connectors for microphone
and headphone
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