When building a PC, the form factor you choose determines everything from how many drives you can install to whether you can fit a 360mm radiator. Here's what each standard means.
ATX: The Standard
ATX (305mm × 244mm) is the most common form factor and the default for any desktop build. It provides the most expansion slots (typically 7 PCIe slots), the most M.2 slots (2–5 on modern boards), and the best VRM layout for CPU power delivery. ATX cases are well-ventilated and accommodate large coolers easily. If you're unsure what to pick, ATX is the right default.
Micro-ATX: Compact Without Sacrifice
Micro-ATX (244mm × 244mm) is ATX with the bottom portion removed. Typically 4 PCIe slots instead of 7. Most users only populate 1–2 slots (GPU + NVMe), so mATX is genuinely capable for most builds. Cases are smaller, cheaper, and still support standard cooling. Great choice for office workstations and gaming builds where desk space matters.
Mini-ITX: Maximum Compactness
Mini-ITX (170mm × 170mm) fits in tiny cases. Only 1 PCIe slot — your GPU takes it all. Usually 2 RAM slots instead of 4. Small form factor cases have limited cooling options and can run hot in Nigeria's climate. Mini-ITX builds require more skill and planning. Recommended for experienced builders with specific space constraints.
Extended-ATX (E-ATX)
E-ATX (305mm × 330mm) is the largest standard consumer form factor. Used for HEDT (high-end desktop) platforms and workstation builds with multiple GPUs or expansion cards. Requires a full-tower case. Very few Nigerian users need E-ATX — it's for extreme workstation configurations.
Making the Decision
Gaming PC with a single GPU: any form factor works. Content creation with multiple storage drives: ATX recommended. Office workstation in a small space: mATX is ideal. Portable LAN gaming rig: Mini-ITX if you can handle the constraints.