A closer look inside
QNAP’s TS-251 can slide apart into two pieces by loosening two screws on the rear of the unit, much in the same way as the units without hot-swap are built. The only reason you’ll need to do this is if you wish to upgrade the memory.
As you can see on the photo below, upgrading the memory isn’t the easiest task in this NAS, but it isn’t difficult either. Four screws to take the entire chassis out from the other half of the chassis and another five to take the top off. Now you got free access to the RAM slots and can switch the modules out with other ones if it doesn’t have enough for you by default.
The motherboard in itself is fairly simple. The SATA bridge connects through a PCIe socket, we can see the flash module at the top left, the CPU in the middle, and the memory modules at the bottom and right side of it.
Two chips were placed on the rear side of the motherboard and those are for the Gigabit Ethernet Ports.
The flash module comes from Apacer and is a common used USB module.
The two 2GB DDR3 SO-DIMM modules come from Transcend and run at 1600MHz. These 2GB modules can be replaced with 4GB if you need even more memory in your NAS.
The SATA bridge has its own little controller onboard between the two SATA connectors. It is a Marvell 88SE9215 SATA 3 to PCI Express 2.0 host controller that can handle up to four SATA3 ports. It is the basic model without hardware RAID and AES encryption as the CPU already provides those features. In return, it is cheaper to use than the bigger 9220 and 9230 chips.
There are a few chips on the motherboard too and one of them is the ASMedia ASM1442 chip, a high-speed TMDS level shift IC for HDMI.
and a Fintek F71869AD is an IO chip that offers provides the last functions and sensors that the CPU can’t provide itself.
The LAN controllers are placed on the rear of the motherboard and these are two Intel i210 controllers, one for each Gigabit Ethernet port.
The rest is pretty much handled by the CPU itself. Intel’s lower end CPUs have come a very long way the last years and they seem perfect for NAS usage.