Ĭurrently, the most popular form factor for desktop computers is ATX, although microATX and small form factors have also become very popular for a variety of uses. Desktop cases-and mini-tower cases under about 46 cm (18 in) high-are popular in business environments where space is at a premium. Full-size tower cases are typically larger in volume than desktop cases, with more room for drive bays, expansion slots, and custom or all-in-one (AIO) water cooling solutions. Form factors for rack-mounted and blade servers may include precise external dimensions as well since these cases must themselves fit in specific enclosures.įor example, a case designed for an ATX motherboard and power supply may take on several external forms such as a vertical tower (designed to sit on the floor, height > width), a flat desktop (height < width) or pizza box (height ≤ 5 cm (2 in) designed to sit on the desk under the computer's monitor). Cases are also referred to by their size (such as ATX case, Mini ITX case, etc.) Consequently, personal computer form factors typically specify only the internal dimensions and layout of the case. The size and shape of a computer case are usually determined by the form factor of the motherboard since it is the largest component of most computers. Accessories shown include: a fan controller, a DVD burner, and a USB memory card reader.Ĭases can come in many different sizes (known as form factors).