Mini PCs
Compact desktop computers for the office, next to the TV and for undemanding work — a small box that tucks behind the monitor and draws a fraction of the power of a classic tower. Choose by intended use, by how far memory and drive can be expanded, and by the number and type of video outputs. A barebone arrives without memory, drive or operating system, which you add yourself.
Mini PCs
A full computer shrunk into a box the size of a book — a mini PC saves space on the desk, runs quietly and draws far less power than a classic tower. It suits the office, browsing, use as a player next to the TV or as a small home server; for demanding games, though, its integrated graphics make it a poor fit.
Settle the intended use first — a low-power processor is enough for the office and the web, while photo editing or several monitors call for a stronger range. A mini PC is sold either ready to switch on, with memory, drive and operating system, or as a barebone. A barebone arrives empty and will not start on its own: memory, drive and operating system are yours to add, so allow for that before you buy.
Expandability is the key point — some models have SODIMM sockets and an M.2 or 2.5" slot, so you add memory and a drive later. On others the memory is soldered in place and cannot be expanded, so choose enough capacity at the time of purchase.
How many monitors you can connect is set not only by the number of connectors but also by their version and the integrated graphics — not every mini PC will drive two 4K monitors. Watch the number and type of outputs (HDMI, DisplayPort, USB-C), the version of the USB ports and whether the computer has LAN and Wi-Fi. A VESA bracket also lets you hang the box directly behind the monitor.
The last difference lies in cooling. Passively cooled models are completely silent but throttle performance under sustained load, whereas models with a fan hold performance at the cost of a faint hum. Always follow the manufacturer's instructions, which also cover the supported memory, the drive capacity and the operating temperatures.