I have the same question, which MB to pair with 3900x for unraid? At the moment my eye is on Asus ROG Strix X570-E Gaming, because it has 3 PCI-E x16 slots - one for gaming GPU pass through to VM, second for cheap unraid GPU (not sure if headless mode will work), and 3rd in reserve for future wishes (like SAS card 9207-8i or some capture card, etc). Also this MB has 8 SATA ports for 8 HDDs so I do not have to use SAS card until I would want more than 8 HDDs.
My intended build for reference - https://pcpartpicker.com/list/4KTd7T
This will be my first unraid build, so I would appreciate confirmation from experts that this MB will wok fine?