Advice for NAS build

I am thinking of building a new NAS since I have outgrown my old OMV Raspberry Pi Backup NAS and I have enough of just drawers of old HDDs where I keep local copies of some stuff.

My main goal is to find a cheap motherboard / CPU combo; I don’t mind buying used, but I think I can write off new as business expense. Ideally I’d like to have at least 1 X16 slot for networking (to drop in a ConnectX etc if I decide to upgrade later) and 1 additional X8 or X16 slot to add an HBA, potentially even an external one as I might go with a disk shelf as rack mount cases with hot swap 3.5" seem hard to find here in Germany. Also DDR4 is preferred, since I have that laying around already.

I will initially have 4 8TB and 4 4TB SATA disks, and I also already have 4 8GB DDR4 sticks left over from my desktop; Any pointers are appreciated. I am thinking I need to go quad core or higher ideally, if I want to push above 1Gbit or later down the line, but it seems while AMD APUs are impossible to find cheaply, Intel has no decent cheap motherboards that meet my spec.

Happy for any pointers or ideas.

remember that with TrueNAS (and ZFS) in general, it is best to use ECC RAM.

with that thought in mind, an ASRock AM4 MB, with a RYZEN PRO CPU, will support unbuffered ECC DDR4. and you will have PCIE for days. this is the lowest cost way to build a competent lower power ZFS NAS at the moment.

the next option is to build a EPYC Embedded system. but the mainboards from supermicro and ASRock Rack are limited, and get costly very quickly.

Lastly, used Xeon stuff. power usage will be higher. availability is spotty.

Is ECC really that important for a homelab NAS these days? I’d have thought it is fine to use normal RAM and leave ECC for anything production ready. Epyc is nice, but certainly not a thing for 24/7 operations and German power bills…

Ive been using non ECC ram for zfs in my home lab for 5ish years… it is fine

my suggestion was for a low cost computer with ECC support. if you do not even care about that, then find a pc from a garage sale and be done with it. almost any PC from the last dozen years will have a PCIE slot.