Even before picking out a CPU, once the Silverstone RM21-308 rack mounted case was picked out. It cemented a few of the key features our motherboard would need to have. The biggest of those was the cases support for ITX or mATX. I could have gone with a larger case, Silverstone does have them. But I wanted something somewhat compact. That decision limited my options significantly. Frankly, we don’t get a lot of mATX motherboards in, and a lot of the ITX options which I have a few of would struggle to cover the other three areas that were important to me. So in addition to being mATX or ITX, our motherboard would have to have a way to handle the eight SATA hard drives. This right here eliminated all of the ITX boards I had around. I also wanted to run an M.2 NVMe SSD for the OS drive so I would need one M.2 slot. Then the last important thing was having 4 RAM DIMMS so I could have a good amount of memory. That one also took ITX boards off the table, but I was a little more flexible on that option because 32GB modules are a thing.
So the 8 SATA drives were needed so I could avoid having to add a RAID controller and like I mentioned that took all of the ITX boards off the table. But even with mATX having 8 or more SATA ports is rare, right now on Newegg even you won’t find even one Intel option with 8 or more SATA ports with an mATX form factor and I mean ALL of Intel's chipsets. There are two ASRock options on the AMD side and one would be my first choice but I don’t have it around. So before going to adding to the cost of the build, I found a creative solution using a board I do have around. I could use a board with a U.2 port with an SFF-8643 to SATA cable to expand the SATA capabilities. Let me just also point out that as I am writing this, it is all still untested so this could still all blow up in my face and I would need to go a different route. But As it sits, I just happened to have an mATX board that we previously reviewed on hand that had a U.2 port and at least 4 more SATA ports that fit the bill.
The board I came up with was the EVGA X299 Micro that I reviewed back in 2017, wow time flies… This wasn’t as cutting edge as I would have liked, but it perfectly fits the scraping together old components to build a NAS that perfectly fits this build.
The EVGA X299 Micro was the right form factor and has four memory DIMMs which is good.
The U.2 plug is easy to get at and is right next to the six in total SATA ports giving me 10 SATA ports in total if needed. The Silverstone RM21-308 has the eight hot-swap bays. But there are also two internal 2.5-inch bays as well that I could use for a little emergency expansion if needed.
It also has one M.2 slot and the documentation at least doesn’t have it sharing bandwidth with the U.2 port which was initially a concern of mine. X299 offering a good amount of PCI lanes is a nice bonus giving us three x16 length PCIe slots with two being 16x if only one is used and both runnings at x8 if both are in use and the bottom slot is x4 full time. This means I have a few slots to add on a well. With a 10G or 2.5G network card, for example, a RAID controller if my convoluted solution doesn’t work, or a low profile video card if needed.