I'm running a dual Xeon as you mentioned, through buying ex-fleet parts at less than half price of new ones. Several issues I experienced:
- Lack of motherboard options. I had to purchase new motherboard at a high price since the ones that support dual Xeons are either in an incompatible form factor or simply out-of-stock. I settled with Asus Z9PE-D8 WS with an SSI-EEB form factor.
- Outdated BIOS. I had to order a new, pre-flashed, BIOS chip since the BIOS that came with the motherboard refused to boot with the CPU and memory combo.
- Hard to find suitable ECC RAM. The motherboard only supports limited RAM (speed + latency) configs, and finding those is becoming harder. Availability looks seasonal at times.
- Needs capable power supply. One thing that people often look past is the need of a proper PSU. I had to upgrade to one which support two CPU power connectors.
In the end, I went with one of the Phanteks Enthoo [1] cases. Decent quality without breaking the bank :)
Notes:
What is SIMD support like for Ryzen? Does it do avx2 or something similar?
It's true that server components are generally loud. If you have the room, I recommend my setup - which is to have a (home build) rack in the basement, and run long DisplayPort cables (and USB extension cables) to the desk. Or build a closet around a rack in an office, which can be soundproofed. This does push it to the next level in terms of work involved, obviously (and cost as well if you don't have tools or time to DIY most of it).
This downside is likely to become slightly more serious as time goes on and more software uses avx2; but it's certainly not crippling.
We recently built an 8 core machine for a project for "how far could we push some multi-threaded" workload. The "out of the box" workstation's with 8 cores, at least in NZ, were staggeringly expensive. We managed to knock about 1/3rd to 1/2 off the price by a build our own solution but that's not workable for general purpose machines.
Early indicators for certain types of workflow, Ryzen is a blazingly fast platform at a very attractive price point.