As mentioned, all models in the QNAP TS-x59 Pro series share the same dual-core Intel Atom D510 1.66GHz CPU and 1 GB of DDR2 RAM. The Intel NM10 Express chipset only provides two SATA ports, but the TS-449 Pro and TS-559 Pro are equipped with the Intel ICH9R controller as well, thus offering six additional SATA ports with AHCI support. The integrated power supply, two eSATA ports, four USB ports, and two Intel 8257L gigabit Ethernet controllers are available in all models.
Wider Design, Larger Fan
The fifth drive bay makes the TS-559 Pro housing a bit wider than that of the TS-459 Pro (21 cm and 18 cm, respectively). This allows for the use of a large 120 mm fan, compared to the 92 mm fan in the four-drive bay TS-459 Pro. We did not notice any significant differences in noise levels, though. The height (18.2 cm) and depth (23.5 cm) of the two units are identical, though the 5.1 kg TS-559 Pro is quite a bit heavier than the 3.6 kg TS-449 Pro.
(Almost) Identical Front Panels
The front panels of the two NAS units are almost identical. The only differences are the number of drive bays and the power LED to the left of the TS-559 Pro. Other than that, they share the same power button, One Touch Copy button, LCD display, enter/select switch, and status LEDs for eSATA, USB, LAN, and system state. The drive bays are identical as well.