Motherboard Form Factors: ATX vs mATX vs mITX vs E-ATX

When you're assembling a PC, one of the initial decisions you'll have to make is what size (form factor) motherboard to choose. It may seem bewildering with terminology such as ATX, mATX, mITX, and E-ATX, but don't get confused — it's simply a matter of size and functionality. Let me explain so you can choose the appropriate one for your system.

1. ATX (Advanced Technology eXtended)

• Size: Typical full-size board (approximately 12 x 9.6 inches).
• Features: Ample space for expansion slots (GPUs, SSDs, capture cards). Typically accommodates 4 RAM slots.
• Best for: Most gaming PCs and mid-to-high-end builds.
• Why choose it: Balanced size and features — the "default" for most PC builders.

2. mATX (Micro ATX)

• Size: Smaller than ATX (9.6 x 9.6 inches).
• Features: Fewer expansion slots but still accommodates up to 4 RAM slots.
• Best for: Budget builds or mid-range PCs when you don't want so many extras.
• Why choose it: Less expensive, can fit into smaller cases, and still gets the job done.

3. mITX (Mini ITX)

• Size: Small board (6.7 x 6.7 inches).
• Features: Only 1 PCIe slot, typically 2 RAM slots. Extremely limited expandability.
• Best for: Small form factor (SFF) builds, such as small gaming PCs or HTPCs (Home Theater PCs).
• Why choose it: Ideal if you need a compact, transportable, and minimalist form factor.

4. E-ATX (Extended ATX)

• Size: Larger than ATX (12 x 13 inches).
• Features: Additional room for additional RAM slots (up to 8), improved power delivery, and additional expansion capabilities.
• Best suited for: Enthusiast builds, workstations, or high-end gaming setups.
• Why choose it: Ultimate performance, cooling, and personalization — but requires an enormous case and a fat bank account.

Quick Conclusion

• ATX → The jack-of-all-trades. Ideal balance for the majority of gamers.
• mATX → Smaller, less expensive, but strong enough for budget/mid builds.
• mITX → Extremely compact, ideal for portable builds, but with limited upgrade options.
• E-ATX → Monster mode. For heavy users and workstation owners.

Final Thoughts

Your motherboard size determines your PC case size, expandability, and overall cost. As a new builder, ATX or mATX is most likely the way to go. Take it mITX if you want an extremely small, sleek build, or E-ATX if you're going whole hog.