Choosing a refurbished mini PC for Home Assistant

Our starting choice

For a first, dedicated Home Assistant server, compare complete refurbished machines with 8GB RAM, an SSD and wired Ethernet. The HP ProDesk 400 G5 Mini, i5-8500T, 8GB RAM and 256GB SSD is a concrete budget option: its seller listed £149.99 and 15 in stock on 21 October. VAT inclusion was not explicit, so confirm the checkout total. For ordinary home automation, you do not need to pay for an i7 or 32GB just to get started; the checklist below is for installing Home Assistant OS directly.

What can you buy now on a £150-£250 budget?

The HP 400 G5 Mini had stock directly verified on 21 October. Its seller lists a power adapter, free UK delivery and a one-year warranty; confirm the final tax-inclusive price, BIOS access and actual ports before ordering. HP's platform datasheet marks HDMI as optional, though the seller lists it, so ask for a photo if HDMI matters to your setup.

The M720q with i5-8400T returned to stock at £209 on 3 November, according to its exact retailer SKU. The listing read on that date does not establish the included RAM or SSD: our earlier 8GB/240GB configuration is a dated reference, so ask the seller to confirm both capacities and the power adapter before comparing complete costs.

The £149 Dell 3060 was out of stock on 5 October and its retailer page returned 404 on 21 October; its old price is retained only for comparison. The M710q with i5-7400T, 8GB RAM and 256GB SSD was listed at £149.90 when we last verified its price on 7 September, but the retailer blocked our 2 November retry. Its current price and stock are unknown. Check each seller’s live listing before spending.

The £229 HP 800 G5 was marked available on 5 October, but its current title says i5-9400T while its URL says i5-9500T. Ask the seller which processor, RAM, SSD and power adapter the exact unit includes before ordering. For a dedicated Home Assistant installation, paying extra merely for more CPU cores is unnecessary; a complete machine with working UEFI settings and a clear return policy matters more. Lenovo's M710 Tiny specification lists the 7400T as four cores/four threads, while Intel's 8400T specification lists six cores/six threads. Extra capacity can matter if you also plan several virtual machines.

Already have a spare PC? Run through the checks below before buying another one.

Decide whether this PC is dedicated to Home Assistant

Home Assistant offers a KVM/Proxmox virtual-machine image and lists 2GB RAM and 2 vCPUs as the VM minimum. That is for the Home Assistant guest, not the whole host or your other services. If you use a Zigbee or Z-Wave USB radio, plan how the VM will access that device; Home Assistant's installation guide describes USB passthrough. A virtual machine adds setup and maintenance work. If you just want a reliable appliance, the direct installation below is simpler. Decide before wiping the SSD.

1. Choose the right size of setup

These are planning allowances, not official minimums. A 240GB SSD is fine for our ordinary-automation starting point; paying more solely to reach the finder's 256GB filter gains little.

2. Reject incomplete or locked machines

Ask for these answers before paying:

• BIOS access: no unknown administrator password; you must be able to change boot settings.
• Boot support: 64-bit x86 processor, UEFI available and Secure Boot can be disabled. These are Home Assistant OS requirements.
• Included hardware: the advertised RAM and SSD, a compatible power adapter and a UK mains lead. “Up to 32GB” does not mean 32GB is included.
• Returns: a stated return period and a clear process if the unit is faulty or does not match the description.

Copy this to the seller if the listing is unclear:

Can you confirm the CPU, installed RAM and SSD, included power adapter and UK lead, and that the BIOS has no administrator lock? I need UEFI boot with Secure Boot disabled.

If the seller cannot confirm BIOS access, choose another unit. Between similarly priced complete offers, favour a clear configuration and return policy.

3. Budget for the connection to your devices

Connect the PC to your router by Ethernet. If you want to pair Zigbee devices directly through Home Assistant's ZHA integration, you also need a supported Zigbee coordinator. The PC's Wi-Fi or Bluetooth does not replace it. If your devices already work through an existing compatible hub, investigate that integration before buying another radio.

Plan where the Zigbee radio will sit before choosing a permanent PC location. Home Assistant's interference guidance explains that USB 3.x equipment can interfere with Zigbee reception.

• Use an adequately shielded USB extension cable and a USB 2.0 port. Position the coordinator away from the PC, USB 3 devices and Wi-Fi access points.
• If the PC only has USB 3.x ports, Home Assistant recommends a powered USB 2.0 hub for the coordinator. Include that accessory in your buying comparison.
• Test a device in the room where you need it before fixing the PC and radio out of sight. If reception is unreliable, follow the interference checks and try another radio position before spending on a faster computer.

4. Set it up, then prove it works

1. Gather a monitor, keyboard, Ethernet cable and an 8GB-or-larger USB stick. Back up anything on the PC: writing Home Assistant OS erases the target drive.
2. Enable UEFI and disable Secure Boot. Follow the official Ubuntu USB installation method to write Home Assistant OS to the internal SSD. The USB stick is the setup tool, not the final system drive.
3. Remove the USB stick, connect Ethernet and boot from the SSD. Complete onboarding using the official instructions.
4. Add one device and make one automation work. Reboot and check it still works before moving the PC out of sight.
5. Create a backup and keep a copy on another device. Complete the recovery checklist below before building a configuration you would hate to recreate.

If the PC says “no bootable device”

Check the installation before replacing the PC or SSD. These steps apply to Home Assistant OS installed directly on the internal drive, not a virtual machine.

1. Confirm that the HAOS image was written to the internal SSD. Running successfully from a USB stick does not install it there automatically. If you used the Ubuntu method, shut down and remove that USB stick before testing the SSD boot.
2. Recheck UEFI enabled and Secure Boot disabled, then select the internal drive in the boot menu. Use the manufacturer’s instructions for your exact model; menu names vary.
3. If the drive is detected but no boot entry works, follow the official Home Assistant startup troubleshooting. It describes adding an EFI boot entry. Identify your actual drive before following its command; do not guess a disk name or erase the drive again.
4. If the SSD is not detected by the firmware, investigate that hardware problem with the seller before buying replacements.

Home Assistant also requires a boot drive with 512-byte logical sectors: 512n or 512e. A native 4Kn-only drive is unsuitable; this does not rule out NVMe drives in general. Ask the seller to confirm the exact drive if that detail is unknown.

Check restart after a power cut

A successful reboot does not prove the PC will start when mains power returns. Before buying, ask whether its unlocked firmware can start it automatically after a power loss.

For example, Dell’s OptiPlex 5070 Micro manual calls this AC Recovery and lists Power Off, Power On and Last Power State; Power Off is the documented default. For an unattended server that should start whenever power returns, check the exact model’s instructions for its Power On setting. A scheduled start time or Wake on LAN is a different feature; menu names vary between machines.

During setup, back up first, select the supported power-on setting and save it. Shut the system down cleanly, wait until it is fully off, then disconnect and restore its mains supply. Check whether it starts without pressing the button, Home Assistant becomes reachable and your sample automation works. Do not pull power from a running installation for this check.

This checks the selected restart behaviour; it does not establish protection from abrupt outages or replace the external backup below.

5. Keep a recovery plan outside this PC

A backup saved only on the mini PC cannot help if its SSD fails. Reserve a separate storage destination before spending the whole budget on the machine.

1. Open Settings > System > Backups and configure automatic backups.
2. Keep a backup copy outside this Home Assistant system, where you can retrieve it if the PC stops working.
3. Download the backup emergency kit and store it somewhere safe outside the PC. Encrypted backups need their matching key; keep the older kit if you later change keys.
4. Write down where the backup and kit are stored. Check that you can retrieve both from another device.

Home Assistant says an encrypted backup cannot be restored without its matching key. A larger SSD does not replace this recovery plan. These are setup checks for the owner, not a claim that we have tested restoration on a catalogue machine.