What Is a Single Board Computer? SBC Form Factors, Uses and Industrial Boards

A single board computer (SBC) is a complete computer built on one circuit board: the processor, memory, storage, power regulation and input/output connectors all sit on the same board, so it can run an operating system and an application with nothing more than a power supply and, if needed, a display. There are no separate memory sticks, drives or expansion cards to assemble before it works.

That definition covers two quite different worlds. Maker boards such as the Raspberry Pi brought SBCs to students, hobbyists and prototypers. Industrial single board computers do the same job inside machines, kiosks, medical devices, vehicles and control cabinets, where they have to run for years across a wide temperature range and stay available for the life of the product.

This guide explains what is on an SBC, the main form factors from the 1.8 inch Femto-ITX to PC/104 and EPIC, x86 and Arm processors, how SBCs compare with motherboards, systems on module and microcontrollers, the differences between maker and industrial boards, where SBCs are used and how to choose one.

A form factor fixes a board’s outline, mounting holes and, for stackable formats, its expansion connectors, so enclosures and accessories can be designed around it. The industrial SBC formats below are listed from smallest to largest. Their names are the standard way to specify the size; the exact outline for each is in the relevant specification.

Larger boards, from Mini-ITX upwards, are generally called motherboards rather than SBCs, because they use socketed memory and full-size expansion slots and are built into a chassis like a PC; our range of industrial motherboards covers them. Our explainer on motherboard form factors sets out the full list.

Femto-ITX and Pico-ITX boards show how far x86 computing has shrunk. The 1.8 inch Femto-ITX SBC is among the smallest commercially available formats, and boards such as the DFI TWLF51 series fit eight-core Intel Core 3 N355 or Intel Atom x7000RE processors, 8 GB of soldered LPDDR5 memory and 64 GB of eMMC onto it, with a 12 V DC terminal block input. Their small footprint suits compact IoT devices, small controllers and OEM housings where space is the first constraint, and their low power suits sealed and battery-powered equipment.

Slightly larger, the 2.5 inch Pico-ITX SBC offers more room for connectors and a more powerful processor. The DFI WCL051-BT-350 carries a six-core Intel Core 7 350 Wildcat Lake processor with Xe3 graphics and dual 2.5GbE, while the Avalue ACP-Q6490 puts an Arm Qualcomm QCS6490 with a 12 TOPS AI engine on the same format. Pico-ITX boards suit digital signage, portable medical devices, drones and compact HMIs, where they balance size against performance and I/O.

The 3.5 inch SBC, also called a 3.5 inch embedded board, is the most common industrial format. It has room for a full set of industrial I/O: the Sintrones SMB-2615, for example, offers Intel Processor N150, Core 3 N355 or Atom x7433RE processors with dual 2.5GbE, four COM ports, a DDR5 SO-DIMM socket, TPM 2.0 and a watchdog. Rugged 3.5 inch boards such as the Diamond Systems VNS776KL-4GD combine a Core i7 with soldered memory, latching connectors, −40 to 85 °C operation and PCIe/104 OneBank expansion.

The 4 inch EPIC SBC gives more board area again. The DFI HPT253-BCN-8640U uses it for a six-core AMD Ryzen 5 8640U with a 9 to 36 V DC input, triple LAN and three M.2 slots for a 4G or 5G modem, Wi-Fi and an NVMe SSD.

The PC/104 family takes a different approach: boards stack on top of each other through their expansion connectors, so I/O, power and network boards build up into a rugged, self-contained system without a backplane. PC/104 single board computers remain common in defense, aerospace and transport, and our guides explain what PC/104 is and the PC/104 bus variants.

At the heart of any SBC is its processor, and the rest of the board follows from it: the memory type it supports, the number of PCIe lanes and USB ports it brings out, its graphics and its power draw. The table lists what you will find on a typical industrial board and what to look for.

M.2 sockets deserve a special mention. They have largely replaced Mini PCIe and mSATA for storage and wireless on SBCs, and small M.2 2230 and 2242 SSDs are a good fit where board space is tight. The socket’s key decides what fits: our guide to M.2 key types explains which modules go where, including 4G and 5G modems, Wi-Fi and GNSS for devices that need location.

Industrial SBCs are built on two processor architectures, and the choice usually comes down to software. Intel single board computers range from efficient Atom and Processor N parts to Core and Core Ultra, and AMD Ryzen Embedded SBCs add strong integrated graphics. Arm SBCs are known for low power, integrated multimedia and, increasingly, built-in NPUs for AI inference.

Where the application already runs on Windows, an x86 board with Windows 11 IoT Enterprise LTSC is usually the shortest route. Where power, cost and Linux are the priority, Arm boards such as our NXP i.MX SBCs fit well. Our comparison of x86 and Arm for industrial use goes into more depth, and our guide to AMD Ryzen Embedded boards covers the AMD side.

The board is only half the decision; the software it runs, and who maintains that software, matters as much over a product’s life. On x86 boards the firmware is a UEFI BIOS, so Windows and mainstream Linux distributions install much as they would on a PC, and the board maker supplies drivers for the network, graphics and I/O controllers. Settings such as boot order, watchdog behavior, power-on after power loss and serial port modes are configured in the BIOS, and we lock them down as part of each build.

Arm boards work differently. Each one comes with a board support package from its maker: the boot loader, kernel, drivers and device tree for that board, usually delivered as a Linux image or as layers for the Yocto Project. Application teams build on that BSP, so its quality and the maker’s update policy decide how easily the product can be patched later. Our introduction to embedded Linux explains the common approaches.

Whichever route a project takes, keep a record of the exact image, BIOS version and board revision on each system. When a board is revised, as long-life boards occasionally are, that record is what lets the new revision be checked against the old one rather than treated as a new design.

Three kinds of board can sit at the centre of an embedded product, and the choice affects cost, flexibility and how the product is upgraded.

An SBC is the simplest choice when one board already has the right I/O and fits the enclosure. A motherboard, such as an industrial Mini-ITX motherboard, suits builds that need full-size PCIe cards or more memory. A system on module suits products that need custom I/O or a processor upgrade during their life. Our guide to choosing an industrial motherboard or embedded SBC works through the decision.

A microcontroller (MCU) is a single chip with a small processor core, a little memory and peripherals, running firmware or a real-time operating system directly. An SBC is a full computer that boots an operating system such as Linux or Windows. Many products use both: the SBC runs the application, user interface and networking, while a microcontroller handles fast, deterministic control close to the hardware.

Is a Raspberry Pi a single board computer? Yes, and it is the best-known one. Maker boards made SBCs cheap and familiar, and they are excellent for learning, prototyping and some commercial uses such as Raspberry Pi digital signage. The differences from an industrial board show up when the product has to run unattended for years in a cabinet, a vehicle or outdoors.

Temperature is the difference that most often decides it. Inside a sealed enclosure in the sun, or a cabinet next to drives, a board can see 20 °C or more above the outside air, which our explainer on the industrial temperature range covers. Boards in our rugged single board computers range are built and rated for those conditions.

Industrial SBCs are built into equipment rather than sold as a computer in their own right. They find their way into smart manufacturing lines, robotics, surveillance networks, energy management and rugged communication devices, often running around the clock. The table shows where each format tends to appear.

Many of these roles connect sensors and machines to a network. Power-over-Ethernet boards, such as our PoE SBCs, can power IP cameras and sensors from the board, and the same boards sit inside many IoT gateways. Where the application needs Linux, our Linux SBCs run the distributions their makers support.

For most fixed designs the advantages win, which is why SBCs are so common in industrial equipment. Where the disadvantages bite, a system on module or a motherboard is usually the answer.

These boards cover the main industrial form factors and both processor architectures. We fit memory, storage and wireless, configure the BIOS, image the operating system and application, and test each board before it ships, or build it into a complete enclosure where the project needs one.

For a complete computer rather than a bare board, the same processors appear in our fanless box PCs, and our ASRock Industrial single board computers add further options.