QNAP TVS-871U-RP-I3-4G 8-Bay Rackmount Port RJ-45: 4 x Gigabit RJ-45 Ethernet port (Expandable up to 8 x 1 Gb LAN or 4 x 10 Gb + 4 x 1 Gb LAN by installing optional dual-port 10 Gb and 1 Gb network card) Port USB: 4x USB 3.0 port (rear) 4x USB 2.0 port (rear) HDD Interface: 8 x 3.5-inch SATA 6Gb/s, SATA 3Gb/s hard drive or 2.5-inch SATA, SSD hard drive Port Others: 2 PCIe Slots (1 x PCIe Gen3 x8, 1 x PCIe Gen3 x4) Form Factor: 2U, Rackmount Operating System: QTS 4.1 Processor: Dual-core Intel Core i3-4150 3.5 GHz Processor Default/ Max. Memory: System memory: 4GB DDR3 RAM Memory module pre-installed: 2GB x2 Total memory slots: 4 Memory expandable up to: 32GB (8GB x4) Note: When upgrading RAM to more than 20GB, the original 2GB RAM modules must be removed.