QNAP USB 3.0. SATA 6Gbp/s Up to 3 GB DDRIII RAM 5-Bay Turbo NAS Tower Server TS-559 ProII Designed with next-generation technology like 6Gb/s (SATA III) hard drives support, delivering blasting fast data transfer speeds Houses up to five hot-swappable 3.5-inch or 2.5-inch SATA hard disk drives for up to 18TB of networked storage (based on 3TB drives). The TS-559 Pro II features 1GB of high performance DDRIII RAM, which can be upgraded to 3GB by simply adding a 2GB RAM in the additional RAM slot. The TS-559 Pro II NAS supports super high-speed USB 3.0 ports, eSATA ports, and VMware vSphere4 (ESX 4.0 and above) and Citrix XenServer virtualization platforms, and is also compliant with Windows 2008 Failover Cluster. Dual Gigabit network interfaces with load-balancing and failover support. Supports NAS and iSCSI applications.