Dell OptiPlex 755 User Manual page 242

Audio
Type
Stereo conversion
Controllers
Drives
Expansion Bus
Bus type
Bus speed
Drives
Internal/External
Connectors
External connectors:
Serial
Parallel
Video
Network adapter
USB
Audio
System board connectors:
SATA
Fan
242
Ultra Small Form Factor Computer Specifications
ADI 1984 High Definition Audio
24-bit analog-to-digital; 24-bit digital-to-analog
one serial ATA controller supporting one device
SATA 1.0a and 2.0;
USB 2.0
SATA: 1.5 and 3.0 Gbps;
USB: 480 Mbps
one D-module bay for an optical drive, second hard drive, or floppy
drive
one bay for a 3.5-inch hard drive
9-pin connector; 16550C-compatible
25-pin connector (bidirectional)
28-pin DVI connector
RJ45 connector
two front-panel and five back panel USB 2.0–compliant connectors
two back panel connectors for line-in and line-out; two front-panel
connectors for headphones and microphone
7-pin connector
one 3-pin and two 5-pin connectors