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Motherboard vs. Circuit Board: What's the Difference?

Posted:02:52 PM January 23, 2024 writer: Roland Pelayo


In electronics and computing, the terms "motherboard" and "circuit board" are often used interchangeably, leading to confusion among enthusiasts and casual users alike. While both play crucial roles in the functioning of electronic devices, they serve distinct purposes. In this article, we'll explore the differences between motherboards and circuit boards, shedding light on their functions, components, size, and costs, and providing a comprehensive comparison.

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Motherboard vs. Circuit Board

At a glance, the terms "motherboard" and "circuit board" might seem synonymous, but understanding their roles reveals their unique characteristics.

A circuit board is a fundamental component in electronic devices, serving as a platform for the connection of various electronic components. It is a flat, rigid board usually made of materials like fiberglass or epoxy, with conductive pathways etched or printed onto its surface to facilitate the flow of electricity.

On the other hand, a motherboard is a specific type of circuit board that acts as the central hub of a computer. It provides a foundation for essential components such as the CPU, memory, and expansion slots, enabling communication between these elements. In essence, all motherboards are circuit boards, but not all circuit boards are motherboards.

Another way of differentiating between a motherboard and a circuit board is the intended use. A motherboard is almost exclusively used for a computer. Circuit boards can be found in other electronic devices aside from computers.


Circuit boards function as a medium for electrical connections, ensuring that various electronic components in a device can communicate effectively. They provide the structural and electrical foundation for the assembly of a wide array of electronic gadgets, from calculators to smartphones.

Motherboards, however, go beyond mere connectivity. They serve as the nerve center of a computer, managing data traffic between the CPU, RAM, storage devices, and other peripherals. In addition to providing connectivity, motherboards also host essential components like BIOS/UEFI firmware, power regulation circuits, and connectors for peripherals.

At the core of the motherboard, the CPU socket accommodates the central processing unit (CPU), facilitating its connection to the rest of the system. Memory slots, typically in the form of DIMM slots, house the system's RAM modules. Expansion slots, often in the form of PCI Express (PCIe) slots, enable the connection of various expansion cards, including graphics cards and network adapters.

The chipset, comprising the Northbridge and Southbridge or their modern equivalents, manages data flow between the CPU, memory, storage devices, and peripherals. Storage connectors, such as SATA and M.2 slots, facilitate connections to hard drives and solid-state drives. Power connectors, including the 24-pin ATX and CPU power connectors, link the motherboard to the power supply unit. I/O connectors on the rear panel offer ports for peripherals like USB devices, audio equipment, and display interfaces. 

Additional components include the BIOS/UEFI chip for firmware, CMOS battery for memory retention, front panel connectors for case buttons and LEDs, USB headers for internal connections, audio headers, network interfaces, cooling solution connectors, and features like debug LEDs or displays for diagnostics and onboard buttons for system control. The combination of these standard motherboard components provides the fundamental infrastructure for a computer system.

A circuit board, commonly referred to as a printed circuit board (PCB), comes in various types to cater to diverse electronic applications. Single-sided PCBs have components mounted on one side with copper traces exclusively on that side, suitable for simpler electronic devices. In contrast, double-sided PCBs allow components on both sides, interconnected through plated through-holes, enabling more intricate circuit designs. Multi-layer PCBs, consisting of more than two layers of conductive material, offer heightened complexity and density, commonly applied in advanced electronics like computers and smartphones.

Rigid PCBs are constructed with an inflexible substrate like fiberglass, suitable for applications where flexibility is not a requirement. Flexible PCBs, made from materials like polyimide, can be bent or twisted to some extent, ideal for space-limited scenarios or flexible wearable devices. Rigid-flex PCBs combine the stability of rigid boards with the flexibility of flexible ones, frequently employed in complex electronic devices. The choice between single-layer and multi-layer PCBs depends on the application's complexity, with single-layer suitable for simpler designs. High-frequency PCBs are designed to manage high-frequency signals without significant signal loss, commonly found in RF communication and high-speed data transmission applications. Other specialized types include aluminum PCBs, featuring a metal core for efficient heat dissipation in applications like LED lighting, and ceramic PCBs, utilizing a ceramic substrate for high-power applications with exceptional thermal performance.

These are just a few examples, and there are many other specialized types of circuit boards designed for specific purposes and industries. The choice of the type of PCB depends on the requirements of the electronic device and the functions it needs to perform.


Circuit boards and motherboards share common components, such as resistors, capacitors, and integrated circuits. However, motherboards have additional specialized components to support their role in managing complex computer systems. These include the CPU socket, RAM slots, expansion slots (PCIe, PCI, etc.), and various connectors for peripherals like USB ports, audio jacks, and networking interfaces.

As mentioned, all motherboards are circuit boards. How motherboards are made share the same process as circuit boards only in the beginning phase.

The production of circuit boards involves a multi-step process, starting with the design phase where schematic diagrams are created and translated into layout designs using computer-aided design software. These designs are then converted into Gerber files, guiding the fabrication process where the copper foil is laminated onto a substrate, and the PCB is etched, drilled, and plated. 

Following fabrication, the PCB undergoes assembly, with electronic components placed and soldered using automated machines or human operators. With specific components mounted, the circuit board now becomes a motherboard. Quality control checks and functional testing are conducted to ensure the motherboard meets performance standards. The BIOS is installed, and the finished product is packaged for distribution, reaching manufacturers or consumers through retail channels. This comprehensive process, encompassing design, fabrication, assembly, testing, and distribution, ensures the production of functional and reliable motherboards.

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Circuit boards come in various sizes, ranging from small boards found in mobile phones to larger ones in home appliances. Motherboards, being a type of circuit board, also come in different sizes, typically categorized as ATX, microATX, and mini-ITX. The size of a motherboard depends on its intended use, with larger variants offering more expansion slots and features.

ATX, microATX, and mini-ITX are three different form factors for motherboards, each with distinct sizes and specifications. These form factors determine the physical dimensions, layout, and features of the motherboard. Here's a brief description of each:

ATX (Advanced Technology eXtended)

The ATX motherboards are the largest among the three. The standard ATX dimensions are approximately 12 x 9.6 inches (305 x 244 mm). ATX motherboards typically have multiple expansion slots, including several PCI Express slots for graphics cards, sound cards, and other expansion cards. They usually provide four to eight RAM slots for memory modules. ATX motherboards offer a variety of connectors and ports, including USB ports, SATA connectors, and others. 

ATX motherboards are commonly used in mid-tower and full-tower cases, providing ample space for expansion and multiple peripherals. They are suitable for gaming PCs, workstations, and high-performance systems.


The microATX motherboard, also known as mATX, is a smaller form factor compared to ATX. The standard microATX dimensions are approximately 9.6 x 9.6 inches (244 x 244 mm). microATX motherboards have fewer expansion slots than ATX, typically ranging from two to four PCI Express slots, and have usually provide two to four RAM slots. microATX boards offer a similar range of connectors and ports as ATX but with a smaller footprint.

microATX motherboards are suitable for smaller cases, making them a good choice for compact desktops or systems where space is a consideration. They are often used in budget-friendly builds and home theater PCs.


The mini-ITX is the smallest form factor among the three, with dimensions of approximately 6.7 x 6.7 inches (170 x 170 mm). mini-ITX motherboards typically have only one PCI Express slot and two RAM slots. Due to their small size, mini-ITX boards may have fewer ports and connectors, but they still offer a basic set of features.

A mini-ITX motherboard is ideal for building ultra-compact systems, such as small form factor (SFF) PCs, home theater PCs, or portable gaming rigs. Their small size makes them suitable for scenarios where space is at a premium.


The costs associated with circuit boards and motherboards vary significantly based on factors such as size, complexity, and intended application. Generally, circuit boards for simpler devices tend to be more affordable, while motherboards designed for high-performance computing can be relatively expensive due to the integration of advanced features and technologies.


To summarize the differences, a circuit board is a generic term encompassing a broad range of boards facilitating electrical connections. In contrast, a motherboard is a specialized type of circuit board that serves as the central hub in a computer system.

Why Are Circuit Boards and Motherboards Green?

The green color of most circuit boards and motherboards is not a functional requirement but rather a result of the manufacturing process and industry conventions. The green color is primarily due to the solder mask applied to the surface of the board.

Here are a few reasons why many circuit boards and motherboards are green:

Epoxy Resin Solder Mask - The base material of most PCBs is made from a fiberglass-reinforced epoxy resin. This material is typically light yellow or brown. To protect the copper traces on the PCB and prevent unintended electrical connections, a solder mask is applied. The solder mask is a layer of polymer that covers the entire board, leaving openings only where soldering is required. The most common color for this solder mask is green, but other colors such as blue, red, black, and white are also used.

Tradition and Standardization - Green became the conventional color for PCBs many decades ago, and it has since become an industry standard. The green color is associated with the epoxy-based solder mask material that has been widely adopted for its durability and electrical insulation properties.

Visibility of Traces - The green color provides good contrast for the white or yellow silkscreen printing used for component labels, making it easier to read component designations and other information on the board. Other colors may also offer good contrast, but green has become the most prevalent choice.

Supply Chain and Manufacturing - Green PCBs are mass-produced and readily available, which makes them a cost-effective choice for manufacturers. Standardizing on a particular color can simplify the manufacturing process and reduce costs associated with different materials and processes.

While green is the most common color for motherboards, it's worth noting that other colors are also used, especially in custom or specialized applications. The color of the PCB does not affect the performance or functionality of the motherboard; it is primarily a matter of convention, aesthetics, and manufacturing processes.

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Understanding the distinctions between motherboards and circuit boards is crucial for anyone interested in electronics or computing. While circuit boards form the backbone of electronic devices, motherboards play a pivotal role in the functionality of computers. Whether you're assembling your PC or exploring the world of electronics, recognizing these differences enhances your knowledge and proficiency in the fascinating realm of technology.

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