When it comes to builds my mentality is “save shit from the landfill and spend as little as possible” haha

I feel like there is always a push for consumerism in (basically anything, but especially this) space. You’ll read forums and watch youtube videos that show dumb nerds with sponsorships doing a build with an $1800 budget and for what? Running a nas? Jellyfin? Caldav? This stuff doesn’t take a ton of overhead

If you’re running 5 concurrent users with 2-3 transcoding quicksync should handle that. Research this more but in my experience it works fine. For reference my library is all extremely high quality either 1080 remux or 4k remux with hdr/dv whenever possible (so tonemapping is required) and lossless audio (dts-hd, atmos, etc). If your library is like mine this bumps things up a bit and will use more cores - quicksync will handle the video fine but cores will be needed for the audio and the tonemapping of hdr/dv layer. Additionally if you’re like me and have a ton of anime (or just someone who likes subtitles) another core gets taken to burn those in. For my library with 2-3 users this is fine, could probably even handle 1-2 more (maybe, depends on what they watch).

This is where scalability comes in. Pick a case and psu where you have the option for a discrete gpu if it ever becomes necessary. You extend to 15 users or decide you want to run deepseek locally? Picking a motherboard with an extra PCIE x16 slot is helpful. since you’re offloading NAS to the synology you can just get a motherboard with a pcie slot, though getting one with multiple opens the option that down the line you could add an HBA and a second array should the synology run out of space. Again, depends on your long term plans

Look on marketplace, Craigslist, eBay, etc for older hardware. Full desktops use a lot of power, which sucks, but the advantage for you is that they are expensive to ship so they can get sold a bit cheaper sometimes. Sort by distance and filter by used

Read truenas, unraid, proxmox, serve the home forums for lots of info on example builds too. But don’t worry too much about getting it perfect. Remember it can always be a little better (or a lot better) but most of the time the extra power is just going to waste your money. Unless you specifically have a need for like multiple VMs at once, serious LLM stuff, etc something seriously demanding like that?