ATX full-tower cases are the largest computer cases. Full-tower cases have a lot of space for external and internal components. ATX full-tower cases are compatible with the Standard ATX, microATX, and EATX form factors. The ATX (advanced technology extended) form factor is the most commonly used form factor. Because of its popularity, several variants of the ATX form factor exist. Each variant has different specifications for dimensions and number of expansion slots. However, all ATX variants share the following characteristics:- Back plate measurements (6.25 x 1.75). - Power supply specifications, as follows; 24-pin ATX power connector, on/off switch runs from the case to the motherboard, and soft-power control (OS can turn the computer off).- Expansion slot locations and spacing (0.8 between slots).-Mounting hole locations.-CPU location (top of board near power supply).