XL-ATX is a motherboard form factor that is larger than the standard ATX size. It typically measures 12 inches by 13 inches, providing additional space for more components, such as extra RAM slots and additional PCIe slots. This makes it ideal for high-performance systems, including gaming and workstation builds. Due to its size, XL-ATX motherboards require larger cases, often referred to as full-tower cases. These cases not only accommodate the motherboard but also offer better airflow and cooling options, which are essential for maintaining optimal performance in demanding applications.