Argh, that's some $$ for a fanless case! Just buy a decent case with 2-3x silent Noctua or Fractal Design 14" fans. Even with the stock cooler a low-end Ryzen will be that quiet you hardly going to notice it.

If you want to buy a Ryzen system be sure not to get one of the early builds. They have this terrible bug where you get random segfaults or crashes when you utilize all/most of the cores. And don't be disappointed by the performance. You really should see them as 6 or 8 cores + hyperthreading, not as 12 or 16 core CPUs. This hyperthreading is a joke, if you really are going max out all logical cores.