Ask “what should I run Proxmox on” in any homelab community and you’ll get two camps talking past each other, one pushing a mini PC (an Intel NUC-style box, a Beelink, a Minisforum), the other pushing a custom build in a real case with expansion slots. Both are right, for different homelabs. The question isn’t which is objectively better, it’s which set of tradeoffs actually matches what you’re going to do with the box.
What a mini PC actually gets you
Mini PCs (small-form-factor boxes built around a laptop-class or embedded CPU) have become a genuinely strong default for a Proxmox homelab, and it’s worth being specific about why rather than just “they’re popular now.”
Power draw. This is the real headline advantage. A mini PC built around a modern low-power CPU idles somewhere in the 10-20W range and rarely climbs past 30-40W under real homelab load. A comparable custom build in a full case, even with efficient components, is commonly 2-4x that at idle once you account for a discrete motherboard, more RAM slots being populated, case fans, and often a less power-optimized CPU. Run a box 24/7 for a year and that difference is real money, not a rounding error, see the power-draw math in the electricity-cost piece on this site for exact numbers.
Noise and footprint. Mini PCs are close to silent under normal load and small enough to sit on a shelf without needing a dedicated rack or even a dedicated closet. For a homelab living in a living room, office, or bedroom rather than a garage or basement, this matters more than spec sheets suggest.
Reliability and simplicity. Fewer components, fewer fans, no discrete GPU unless you added one, generally means fewer things to fail and less to troubleshoot when something does.
The real limits: fixed or near-fixed RAM ceilings (many top out around 64-96GB even on higher-end models), one or two NVMe slots and no room for spinning HDDs internally (bulk storage has to live externally, on a NAS or a USB/Thunderbolt enclosure), and no room for a discrete GPU, which rules out anything wanting hardware transcoding beyond what the CPU’s integrated graphics can do, or serious passthrough workloads.
What a custom build actually gets you
A custom build in a real case (mini-ITX at the small end, up to a full ATX tower) trades away the mini PC’s power and footprint advantages for genuine expansion room.
RAM and storage headroom. A real motherboard gives you 2-4 DIMM slots (often supporting more total RAM than any mini PC), multiple NVMe slots, and enough SATA ports to run actual internal spinning drives for bulk storage rather than needing an external NAS. If your plan includes running ZFS with a real RAIDZ array of HDDs directly on the Proxmox box rather than pointing at separate NAS storage, a custom build (or a purpose-built NAS chassis) is close to mandatory, mini PCs simply don’t have the drive bays.
GPU passthrough and expansion slots. PCIe slots mean you can add a GPU for hardware-accelerated transcoding (Plex/Jellyfin), passthrough to a VM for AI/ML workloads, add a 10GbE NIC, or add an HBA card for more SATA connectivity. None of that is possible on a mini PC without external, often awkward, Thunderbolt-based workarounds.
Upgrade path. Swap the CPU, add RAM, add drives, add a card, all without replacing the whole box. A mini PC’s upgrade path is usually just RAM and the NVMe drive, everything else is fixed for the life of the unit.
The real costs: meaningfully higher idle power draw, more noise (case fans, possibly a GPU fan under load), a bigger physical footprint that usually wants a dedicated space rather than a shelf, and more components that can individually fail.
The decision, worked through directly
If your homelab is mostly lightweight services, LXC containers, a handful of VMs, monitoring, DNS, reverse proxy, and bulk storage already lives on a separate NAS (or you’re fine with it living there): a mini PC is the better fit. Lower power cost that compounds every month for years, less noise, smaller footprint, and the RAM ceiling most mini PCs offer today (64GB+) comfortably runs a real service stack.
If you want the Proxmox box itself to also be your bulk storage array (drives living in the same chassis, not external), or you’re planning GPU passthrough for transcoding or AI workloads, or you know you’ll want to scale RAM well past what a mini PC supports: a custom build earns its extra power draw and footprint. Trying to force that workload onto a mini PC usually means fighting external storage and Thunderbolt enclosures that are more fragile and more annoying than just building the box that has room for drives in the first place.
A third option worth naming directly: split the roles. Run a mini PC for Proxmox (VMs, containers, the actual compute) and a separate purpose-built NAS (TrueNAS, Unraid, or another Proxmox box, own article on that OS choice elsewhere on this site) for bulk storage, connected over the network. This gets you the mini PC’s power/noise advantage for the always-on compute layer while still getting real drive bays for storage, at the cost of needing two boxes instead of one and a network link between them fast enough not to bottleneck storage access (1GbE is often fine for general use, 2.5GbE or 10GbE matters more once you’re doing anything storage-intensive across that link).
Don’t ignore idle power in the total cost comparison
It’s easy to compare mini PC and custom-build prices as a single upfront number and stop there. Don’t. A custom build that’s $150 cheaper upfront but draws 60W more at idle than a mini PC, run 24/7 for three years, costs meaningfully more in electricity than the upfront savings, depending on your local electricity rate. Price the hardware and estimate the running cost together before deciding purely on sticker price.
Bottom line
Mini PCs win on power, noise, and footprint, and they’re the right default for a compute-focused Proxmox box that doesn’t need internal bulk storage or GPU passthrough. Custom builds win on expansion room, RAM ceiling, and the ability to hold real drives and cards, and they’re worth the extra power draw once your plans genuinely need that room. If you’re not sure yet, a mini PC plus a separate NAS is usually the more flexible starting point than a single box trying to do both jobs at once.