Dell OptiPlex 990 MT Core i5-2400 3.10GHz 4GB 500GB DVD+/-RW Windows 7 Pro 64-Bit Processor: Intel Core i5-2400 3.10GHz; 4 Cores, 4 Threads; 6MB L3 Cache; Memory: 4GB DDR3 Installed; Hard Drive: 500GB 7200RPM 3.5" SATA Operating System: Windows 7 Professional 64-Bit Installed with Recovery / Reinstalla tion Partition and Certificate Of Authenticity; Optical Storage: CD/DVD+/-RW DL Super Combo; Power Supply: 300 Watt Graphics: Integrated High Definition Video; Audio: Integrated HD Audio Device; Communication: Integrated Intel Gigabit Ethernet Controller 10/100/1000 Front I/O Ports: 4 USB 2.0, 1 Headphone / Audio Out, 1 Microphone / Audio In Rear I/O Ports: 6 USB 2.0, 1 VGA, 1 DisplayPort, 1 Audio Out, 1 Audio In, 1 Ethernet (RJ-45), 2 PS/2