QNAP TS-453U-RP Diskless System 4-Bay Rackmount Port RJ-45: 4 RJ45 Gigabit Ethernet ports Port USB: 4 x USB 3.0 1 x USB 2.0 HDD Interface: 4 x 3.5 or 2.5 SATA 6Gb/s, SATA 3Gb/s hard drive or SSD Port Others: 1 x HDMI 1 x console (system maintenance) Form Factor: 1U, rack mountable Operating System: QTS 4.1 (embedded Linux) Processor: Quad-core Intel Celeron 2.0GHz (up to 2.42GHz) Default/ Max. Memory: 4GB DDR3L SDRAM (1 x 4GB) 2 x SODIMM (Max: 8GB)