Mini-ITX is a motherboard size standard that measures 170 × 170 millimetres. It is the smallest standard motherboard format still widely available for consumer PCs, designed to fit into compact cases whilst retaining a single PCIe expansion slot and enough features for most users.
The format originated in the early 2000s as a space-saving alternative to the larger ATX and micro-ATX boards. Today, Mini-ITX boards appear in three main contexts: small form factor gaming PCs, media centre systems, and office computers where desk space is limited.
A typical Mini-ITX motherboard includes one full-size PCIe slot (usually x16), two or three RAM slots, and onboard sound and networking. Storage connects via SATA or M.2. Because the board is small, cooling solutions and power delivery components are more tightly packed, which can matter if you plan to overclock or use power-hungry processors.
Real-world example: someone building a PC to fit on a shelf next to their TV might choose a Mini-ITX motherboard paired with a compact case, a modest GPU, and a low-power CPU to keep heat and noise down.
When shopping, check that your Mini-ITX board has enough slots and headers for your storage drives, fans, and USB needs. Verify the case supports your chosen cooler height, as space above the socket is tight. If you want future upgrade room or multiple graphics cards, a larger form factor will serve you better.