Are All Motherboards the Same Size? (Variety in Form Factors)

Motherboards are often referred to as the backbone of a PC.

It is the main printed circuit board that allows all components such as the processor, memory, and storage devices to communicate and work together seamlessly.

However, not all motherboards are created equal. In fact, one of the most common questions among computer enthusiasts is, “Are all motherboards the same size?”

The answer is no. Motherboards come in different sizes and formats, each with its own unique features and capabilities.

Understanding these differences is crucial when selecting the right motherboard for your computer build.

In this article, we will explore the various motherboard sizes and what makes each one unique, so you can make an informed decision when building your next computer.

Common Motherboard Form Factors

The first and foremost difference to be aware of is the form factor, which refers to the physical size and shape of a motherboard.

AspectATX (Advanced Technology Extended)Micro ATX (mATX)Mini-ITX
Size12 x 9.6 inches (30.5 x 24.4 cm)9.6 x 9.6 inches (24.4 x 24.4 cm)6.7 x 6.7 inches (17 x 17 cm)
Use CasesGaming rigs, workstations, full-sized casesCompact desktops, HTPCsUltra-compact systems, HTPCs
Expansion SlotsMultiple PCIe slots for graphics cards, additional cardsFewer PCIe slots, limits expansionTypically one PCIe slot
RAM SlotsUsually 4 to 8 RAM slotsTypically 2 to 4 RAM slotsTypically 2 RAM slots
Cooling SupportAdequate space for large CPU coolers and multiple case fansLimited space for cooling solutionsLimited space for cooling solutions
Storage ConnectorsMultiple SATA and M.2 connectorsFewer SATA and M.2 connectorsFewer SATA and M.2 connectors
Case CompatibilityRequires standard ATX casesCompatible with mATX and some ATX casesCompatible with Mini-ITX cases
User BaseEnthusiasts, gamers, professionalsBudget builders, compact systemsCompact system enthusiasts
Price RangeModerate to highBudget to mid-rangeMid-range to high

ATX (Advanced Technology Extended)

The ATX form factor is one of the most prevalent motherboard sizes and measures 12 x 9.6 inches (30.5 x 24.4 cm). ATX motherboards are commonly found in desktop PCs and tower cases. They offer ample space for various components, making them suitable for gaming rigs and workstations.

Characteristics of ATX motherboards:

  • Standardized Design: ATX motherboards have a consistent layout with specific locations for components like the CPU socket, RAM slots, and expansion slots, which makes them user-friendly and compatible with various cases and peripherals.
  • Multiple Expansion Slots: They typically have multiple PCIe slots for graphics cards, additional USB cards, sound cards, and more, allowing for extensive customization.
  • Adequate Cooling Options: ATX motherboards provide ample space for cooling solutions, including large CPU coolers and multiple case fans.
  • Sufficient RAM Slots: Most ATX motherboards feature four to eight RAM slots, accommodating a significant amount of system memory.
  • Multiple Storage Connectors: They support multiple SATA and M.2 connectors for various storage options.

Micro ATX (mATX)

Micro ATX motherboards are more compact compared to ATX , measuring a modest 9.6 x 9.6 inches (24.4 x 24.4 cm). They strike a balance between size and features, making them suitable for compact desktops and budget-oriented builds.

Characteristics of Micro ATX motherboards:

  • Compact Design: Micro ATX motherboards are smaller, which makes them a good choice for smaller PC cases and HTPCs (Home Theater PCs).
  • Fewer Expansion Slots: They typically have fewer PCIe slots, limiting the number of add-on cards that can be installed.
  • Limited RAM Slots: Micro ATX motherboards often have two to four RAM slots, accommodating less system memory compared to ATX boards.
  • Basic Cooling: Due to their smaller size, they may have limited space for elaborate cooling solutions, but many still support standard CPU coolers and case fans.


Mini-ITX motherboards are the smallest commonly available form factor, measuring just 6.7 x 6.7 inches (17 x 17 cm). These tiny motherboards are ideal for compact, space-constrained builds.

Characteristics of Mini-ITX motherboards:

  • Compact and Lightweight: Mini-ITX motherboards are incredibly small and lightweight, making them suitable for ultra-compact systems, such as home theater PCs and gaming consoles.
  • Single PCIe Slot: They typically have only one PCIe slot, which limits the number of expansion cards that can be added.
  • Limited RAM Slots: Mini-ITX boards usually come with two RAM slots, which restricts the amount of system memory that can be installed.
  • Minimal Cooling: Due to their size, cooling options are limited. Users often rely on low-profile or stock cooling solutions.
  • Fewer Ports: These motherboards may have fewer USB ports and storage connectors compared to larger form factors.

Less Common Form Factors

While ATX, Micro ATX, and Mini-ITX are the most widely used motherboard form factors, there are other less common form factors designed for specific applications and purposes:

AspectEATX (Extended ATX)Nano-ITX
SizeLarger, up to 12 x 13 inches (30.5 x 33 cm)Extremely compact, 4.7 x 4.7 inches (12 x 12 cm)
Use CasesHigh-end workstations, servers, extensive configurationsSpecialized applications, industrial systems, embedded computing
Expansion SlotsMultiple PCIe slots for graphics cards, extensive expansion optionsLimited to one PCIe slot
RAM SlotsUsually 8 or more RAM slotsTypically 1 or 2 RAM slots
Cooling SupportAmple space for advanced cooling solutions, suitable for high heat outputLimited space for cooling, often relies on low-profile or stock coolers
Storage ConnectorsMultiple SATA and M.2 connectorsLimited SATA and M.2 connectors
Case CompatibilityRequires specific EATX cases designed to accommodate the larger sizeCompatible with Mini-ITX cases, often custom or specialized
User BaseProfessionals, server builders, those requiring extensive hardware configurationsIndustrial users, embedded system designers
Price RangeHigh-end due to extensive features and capabilitiesVariable, can be higher due to specialized use cases

Extended ATX (EATX)

Extended ATX motherboards, as the name suggests, are larger than standard ATX boards. They can measure up to 12 x 13 inches (30.5 x 33 cm) or even larger. EATX motherboards are typically used in high-end workstations and servers where extensive hardware configurations are required.

Characteristics of Extended ATX motherboards:

  • Extra PCIe Slots: EATX motherboards provide additional PCIe slots, allowing for more graphics cards and other expansion cards.
  • Enhanced Cooling Support: They often have more space for advanced cooling solutions, making them suitable for systems that generate a lot of heat.
  • Numerous RAM Slots: EATX motherboards can accommodate a large amount of system memory, often featuring eight or more RAM slots.
  • Large Chassis Required: Due to their size, EATX motherboards require larger PC cases designed specifically to fit them.


Nano-ITX motherboards are even smaller than Mini-ITX, measuring a mere 4.7 x 4.7 inches (12 x 12 cm). These tiny motherboards are primarily used in specialized applications, such as industrial systems and embedded computing.

Characteristics of Nano-ITX motherboards:

  • Extremely Compact: Nano-ITX motherboards are among the smallest available, allowing for compact and space-efficient system designs.
  • Limited Expansion: They typically have only one PCIe slot and fewer RAM slots, making them unsuitable for gaming or high-performance applications.
  • Industrial Durability: Nano-ITX motherboards are often built with rugged components to withstand harsh environments.
  • Specialized Connectors: They may feature unique connectors tailored for specific industrial or embedded applications.

Factors Influencing Motherboard Size

Let’s take a closer look at some of the factors that influence motherboard size:

Component Placement and Layout:

Explanation: The physical arrangement of components, including the CPU socket, RAM slots, and expansion slots, plays a significant role in determining the size of a motherboard. Different form factors have standardized layouts to ensure compatibility with various cases and components.

Impact: Component placement dictates the overall shape and dimensions of the motherboard. This influences how well the motherboard fits within a specific case and how components can be connected to it.

Cooling Requirements:

Explanation: Efficient cooling is crucial for a computer’s performance and longevity. The size of a motherboard can affect the available space for cooling solutions, such as CPU coolers, GPU coolers, and case fans.

Impact: Larger motherboards often offer more space for advanced cooling solutions, making them suitable for high-performance systems that generate significant heat. Smaller motherboards may require specialized or compact cooling solutions.

Number of Expansion Slots:

Explanation: The number and type of expansion slots, like PCIe slots, required for a user’s hardware configuration significantly impact motherboard size. Different form factors accommodate varying numbers of expansion slots.

Impact: Enthusiasts and professionals needing multiple graphics cards, additional storage controllers, or specialized expansion cards may opt for larger motherboards with more PCIe slots. Smaller motherboards limit the number of expansion options available.

RAM Capacity:

Explanation: Motherboard form factors also influence the number of RAM slots and maximum RAM capacity supported. Different sizes provide varying levels of support for system memory.

Impact: Users with extensive RAM requirements, such as content creators and professionals, should choose motherboards with more RAM slots and higher maximum RAM capacity to meet their needs.

Case Compatibility:

Explanation: The motherboard’s size must match the case’s form factor to ensure proper fitment. Cases come in various sizes, including ATX, Micro ATX, Mini-ITX, and more.

Impact: Choosing a motherboard that aligns with the case’s form factor is essential for ease of installation and ensuring all components fit correctly. Mismatched sizes can lead to compatibility issues.

User Preferences and Intended Use:

Explanation: Ultimately, the user’s preferences and intended use case play a crucial role in selecting the appropriate motherboard size. Different form factors cater to various needs and system designs.

Impact: Gamers, content creators, and enthusiasts may prioritize specific form factors based on their performance requirements, case preferences, and customization goals. Selecting the right motherboard size aligns with the user’s vision for their computer system.


Motherboards come in various sizes and form factors, each catering to specific needs and preferences.

While ATX, Micro ATX, and Mini-ITX are the most common form factors, extended ATX and Nano-ITX cater to niche markets with specialized requirements.

Understanding the factors that influence motherboard size, such as component layout, cooling needs, expansion options, RAM capacity, and user preferences, is crucial when building or upgrading a computer system.

By selecting the right motherboard size, users can ensure compatibility with their chosen case and components while also planning for future upgrades and enhancements.