A Look Inside

It's now time to strip the NAS down to discover what components are hidden inside its casing.


As with all QNAP boxes, the break-apart process isn't too complex since the one-piece top and side cover is easily removed by unscrewing only three screws. The casing has enough room to accommodate an SFF PSU, but the TS-421 uses an external brick instead. As you will also find out, the TS-421 is a TS-419P II with more RAM (up to 1024 MB from 512 MB).


The small mainboard is underpopulated, and the most important components on the rear side are two RAM chips. There are two on this and two on the opposite side. A total of 1024 MB of DDR3 RAM (Hynix H5TQ2G83CFR) is directly soldered onto the mainboard. You cannot upgrade the RAM total since there are no DIMM slots.


A single-core Marvell 88F6282 SoC is the brains of the NAS. It is cooled by a small, passive heatsink since its thermal dissipation is low. The CPU this SoC integrates is fully ARMv5TE compliant and is equipped with 256KB of L2 cache.


The Ethernet ports are controlled by two Marvell Alaska 88E1318 ICs. Each of these ICs contains a single Gigabit Ethernet transceiver. It implements the physical Ethernet layer of the 1000BASE-T, 100BASE-TX, and 10BASE-T standards.


The GL850G IC of Genesys Logic is the USB 2.0 hub controller. It provides four downstream USB ports.


This PIC16F690 IC is an 8-bit microcontroller and includes, amongst others, twelve A/D channels and two voltage comparators.


The buzzer of the NAS is quite loud.


The 128 Mb serial flash memory of the NAS (25Q128A).


The single-phase VRM (Voltage Regulation Module) that feeds the PCIe card.


The PCIe card to which all four removable drives attach utilizes a Marvell 88SX7042 controller. It supports the SATA II protocol and not the newer SATA 6 Gbps, but the 88SX7042 surely won't bottleneck the system since non-mechanical drives cannot exceed SATA II limits.


The LCD screen functions are handled by a Microchip PIC16F73 8-bit microcontroller.


As per usual for a QNAP product, the cooling fan is provided by Y.S. Tech. Its model number is FD129225LB (90 mm, 12 V, 0.15 A, 1900 RPM, 40.2 CFM, 80000 MTBF), and it uses ball bearings, which will have it last much longer than a sleeve-bearing fan.