DR845 Dell DR845 DELL DR845 Genuine DELL Motherboard For the Optiplex 755 Desktop Chipset: Intel Q35 Express. Processor: Intel Core 2, Intel vPro, Intel Celeron 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 2.0 compliant 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