This machine replaced a QNAP TS-559 Pro+ NAS (file/media server and Transmission), a Ivy Bridge Xpenology (IP Cameras and Minecraft server), and a Sky Lake gaming computer (passed on to child for Minecraft/Sims machine). If you add all these cores (12), memory (64GB), and storage (89TB) up, this one will still have more than all of those combined! This is definitely not an everyone computer, it's more of a server-hybrid. I chose a 4U server chassis for the case to allow for up to 15 trayless hot-swap drives. 4U allows for sufficient height for a GPU to be mounted vertically in the motherboard. This also allows for 156mm of height from the motherboard for a cooler.
I used my owned GPU, power supply, peripherals, a couple of SATA SSDs, and 3 2TB SATA HDDs. I tried to use the Wraith Prism cooler and pair of stock 120mm fans but temperatures got out of control when the GPU was at full throttle. I cut the case with a rotary tool to accept a pair of 140mm fans (one intake, one exhaust), 2 side 80mm fans for intake, and 2 rear 80mm fans for exhaust. I replaced the stock cooler with a Scythe Ninja. Unfortunately, the Scythe Ninja is taller than the specifications indicate (or I interpreted them to indicate): it reaches 161mm above the motherboard rather than 155mm. I had to drill 12 holes in the top of the case to a facilitate the unplanned height.
I chose the Asus PRO WS X570-ACE motherboard for it's PCIe lane magic. While the chipset still only has 20 PCIe lanes (plus 24 on the 3900X), through some PCIe 3 / 4 wizardry, it can still run 3 cards in 8x mode. That's like getting an extra 4 PCIe lanes! Still far short of the 64 lanes on X399 or 72 lanes on TRX40, but still, it's kind of like threadripper-lite on the relatively inexpensive consumer platform. Another bonus is that this card has an onboard U.2 that can be used with a SFF-8643 mini-SAS HD cable to control an additional 4 SATA drives for a total of 8. It's frankly ridiculous that the ACE doesn't have 10GbE LAN given the workstation branding or a USB 3 Gen 2 header.
I prefer to stick with the QVL for memory when selecting ECC memory. In the case of the ACE motherboard, this limits you to three varieties of 2133-CL15 DIMMS, and four varieties of 2666-CL19 (all at 1.2v). Of the three vendors, only SK Hynix makes readily available and identifiable DIMMS. Good luck finding V-Color or Innodisk. "HMA82GU7CJR8N-VK" however is sold by Supermicro and a variety of other vendors. I chose to purchase Supermicro branded DIMMS as they cost $75, about the same as other vendors. One nice thing about purchasing server memory is that is abundantly clear exactly what you are getting. According to SK Hynix product sheet, it's 2Rx8 Hynix C-die. I found in overclocking that it is completely stable for me at 2666-CL14. Above 2666, I would get WHEA errors, but no crashes until 3466.
I found a LSI 9400-16i on eBay for $247.50, which seems like a heck of a deal on a SAS III controller with 4 ports and is even compatible with NVMe. Most importantly, it only uses 8 lanes of PCIe 3. On any other X570 motherboard, I would have just used up the very last of my PCIe lanes! (8x GPU & 8x HBA)
In addition to the owned drives, I added 10 HE8 drives (Sun Oracle branded) that I bought with two years of use in a datacenter. $11/TB is ridiculously cheap for quality HGST drives. I setup the 10 HE8 drives in a 2-way mirror pool, yielding 35.7TB of effective storage space, this is used as shared network storage, media, programs, qBittorent, etc. I setup the Samsung HDDs into a simple pool yielding 5.5TB of storage, this is used by Blue Iris for IP Camera video storage. The Sabrent Rocket is being used as the primary system drive, with the WD Blue SATA SSD being used for games, and OZC Vertex SATA SSD for Adobe Creative Suite.
The spinning drives are mounted in iStarUSA racks. Note that the single-slot rack (BPN-DE110HD) does not come with a fan, so I added a 40mm Scythe Mini Kaze fan. The 2-pin fan header on the iStarUSA rack is smaller than standard (mini-GPU header?). I had to grind down the sides of the Scythe 2-pin connector to allow it to fit. The SATA SSDs are mounted in the EZDIY-FAB faceplate. That faceplate isn't designed for this purpose, but it has holes that will work for lightweight SSDs.
A couple of notes on the iStarUSA D-410 chassis. It has tremendous expansion up front in the 10 half-height drive bays, but only have two 120mm fan mounting spaces makes this incompatible with a powerful GPU that will be consuming a few hundred watts plus a powerhouse CPU. Also note that the case comes with no instructions, not that it needs them... but you get to figure out wires and stuff, which isn't too difficult. The LEDs for HDD indicator and power were mounted in the incorrect slots in my case: the blue power LED should be on the left side, and the red HDD LED should be on the right.
Fans and mesh filters are mounted with flat head 6-32 machine screws: 1.5" (Hillman #46508-F) except for the top four on the rear, which are 2" (Hillman #46508-Q) with OO flat neoprene faucet washers (Hillman #46087-A), 6-32 hex nuts (Hillman #46508-H), and #6 nylon washers (58056-K). The neoprene faucet washers do a great job of absorbing any vibration between the screw and the case, and fit very nicely with the flat head screw.