When planning a custom computer build, the motherboard is your first major decision. It dictates the size of your case, your expansion options, and your overall budget. Most motherboard articles only list dimensions.
However, you need to know which size to use and when.
This overview breaks down the three most common motherboard sizes: ATX, Micro-ATX, and Mini-ITX. We explain the practical reasons to choose each one for your next build.
ATX Motherboards for Maximum Expansion
ATX is the standard size for most desktop computers. It measures 30.5 by 24.4 centimetres. It is the best choice for users who want maximum expandability.
When to Choose ATX
Select this size if you plan to build a high-end gaming PC or a professional workstation. The larger size provides plenty of physical space. This makes it the easiest form factor to assemble and manage cables inside.
Hardware Expansion Capabilities
ATX boards offer the most ports. They typically include four memory slots, multiple M.2 slots for fast SSDs, and several PCIe slots. This allows you to plug in extra graphics cards, sound cards, or Wi-Fi adaptors later.
Micro-ATX Motherboards for Budget and Value
Micro-ATX is a slightly smaller, square board. It measures 24.4 by 24.4 centimetres. It represents the sweet spot for budget-conscious builders.
When to Choose Micro-ATX
Choose this size if you want the best performance for the lowest price. Micro-ATX boards are usually significantly cheaper than their ATX equivalents. These boards fit into both standard mid-tower cases and smaller, compact cases.
Balancing Cost and Features
Most modern Micro-ATX boards still offer four memory slots. They also usually provide at least two M.2 slots for storage. You only lose a few extra PCIe slots. Most users never actually use these extra slots anyway.
Mini-ITX Motherboards for Compact Builds
Mini-ITX is the smallest common size, measuring just 17 by 17 centimetres. It is designed specifically for small form factor computers.
When to Choose Mini-ITX
Use this size if desk space is very limited. It is also ideal if you want a highly portable PC. This tiny board is perfect for clean, minimalist desk setups.
Compromises for a Small Size
To reach this tiny size, you must accept certain compromises. These boards only have two memory slots and one PCIe slot. They are also usually more expensive and much harder to assemble. Cramming powerful parts into a tiny case restricts airflow significantly. You must plan your cooling system carefully to avoid thermal issues.
Motherboard and Case Compatibility
Your motherboard choice directly dictates your case selection. Mounting layouts are standardised, but case sizes are not.
The Standard Compatibility Rule
A larger case can always hold a smaller motherboard. For example, a standard ATX mid-tower can easily hold a Micro-ATX board. The mounting screw holes will still line up perfectly.
Case Constraints and Limits
You cannot put a larger motherboard into a smaller case. An ATX board will not physically fit inside a Micro-ATX case. It will also fail to fit in a Mini-ITX case. Always verify your case specifications before buying your motherboard.
Professional Computer Builds in Adelaide
Choosing the right motherboard requires careful planning for power delivery, port selection, and case layout. A mismatched system leads to physical frustration and wasted money.
If you want a high-performance computer built correctly, we can help. Our team at Computer Repair Adelaide specialises in custom PC builds. We assist with parts selection, physical assembly, and safe thermal configuration. Contact us today to start your next custom computer project.
Frequently Asked Questions About Motherboard Sizes
This depends entirely on your build requirements. For standard builds, Micro-ATX offers the best overall value. ATX is the best choice for maximum hardware expansion. Mini-ITX is ideal if you are building inside a tiny, compact case.
Micro-ATX or standard ATX are the best choices for gaming. They provide plenty of physical space for large graphics cards and multiple memory slots. Mini-ITX can work, but cooling a hot gaming PC in a tiny case is extremely difficult.
You can find this information in a few different places. First, look at the official manual or retail box if you still have them. Alternatively, search for your motherboard model name on the manufacturer's website. The specifications page will list the form factor clearly.
Mini-ITX is the best form factor for low-consumption setups. These small boards require very little electricity to run. They are designed to work with compact, low-wattage power supplies unit to maximize your energy efficiency.
