Can’t beat the AMD 3900x (12-cores, 24-threads) for price/performance. I tend to like Asrock, Asus and Gigabyte for AMD motherboards (in that order). I would suggest 16GB of Crucial ECC DDR4. I prefer nVidia over AMD videocards. Samsung Nvme SSDs are reliable and fast (Intel datacenter SSDs are better for servers). Most Gold-rated power supplies are fine (500 watts is perfect). Spend at least $80-$180 to get a decent case (check eBay and Craigslist).