I/O Slots2 PCI Express Gen3 x16 slots1 PCI Express Gen3 x16 slot - Available ONLY when 2nd CPU is installed.1 PCI Express Gen3 x8 slot - with x16 connector. - Available ONLY when 2nd CPU is installed.1 PCI Express Gen3 x4 slot - with x8 connector1 PCI Express Gen2 x4 slot - with x8 connector1 PCI 32bit/33MHz slot1 Mechanical-only slotFront I/O2 USB 3.0, 1 USB 2.0, 1 Headphone, 1 Microphone, and 1 IEEE 1394aRear I/O1 IEEE 1394a 2 USB 3.0 4 USB 2.0 1 Serial PS/2 keyboard and mouse 2 RJ-45 to integrated Gigabit LAN 1 Audio Line-In, 1 Audio Line-Out, 1 MicrophoneInternal USB6 USB 2.0 ports available by three separate 2x5 headers. Each 2x5 header supports either one HP Internal USB Port Kit (EM165AA) or one 22-in-1 Media Card Reader.Power Supply850WMemory16GBRAMStorage500 GB HDDCPUE5-2643 3.3 GHzOperating systemWindows 7 Pro 64 bitGraphics adapterNot includedTitleHP Z820 Workstation E7V06UC E5-2643 16GB RAM 500GB HDD Win 7ConditionSeller refurbishedContentHP Z820 Workstation, power cord, keyboard, mouseManufacturerHPModelZ820MPNE7V06UC#ABASKUZ820http://www.compeve.com/Products/Workstations/HP/Z820/Z820_compeve__2.jpghttp://www.compeve.com/Products/Workstations/HP/Z820/Z820_compeve__3.jpg