Dell Optiplex 755 SDT Core 2 Duo System Board W/O CPU Chipset: Intel Q35 Express, Supported Processors: Intel Core 2, Intel vPro, Intel Celeron Supported Memory: 4x 667-MHz or 800-MHz DDR2 SDRAM, 64-bit operating system: 8 GB Max Total, 32-bit operating system: 4 GB Max Total, Audio: Integrated ADI 1984 High Definition Audio Peripheral Interfaces: 9-Pin Serial Connector, 25-Hole Parallel Connector, VGA Monitor Connector, Network/LAN Connector, two front-panel and six back panel USB 2.0compliant connectors, two connectors for line-in/ microphone and line-out; two front-panel connectors for headphones and microphone Expansion Capability: PCI 2.3, PCI Express 1.0A, SATA 1.0A and 2.0 Motherboard Part Numbers: U649C, DR845, WX729