How to Choose a Motherboard: A Complete Guide - HP There are 3 major types of motherboards, with slightly different sizes and plug/slot allotments. They range from ATX motherboards (the most) to the Mini-ITX (the fewest). At a minimum, you'll need slots for: USB ports, including the traditional USB 2, and newer USB 3/USB 3.1 and USB Type-C. HDMI and DisplayPort Video.