With the same external dimensions as the MasterBox Q300L, support for a standard ATX motherboard has been provided. This was made possible by maximizing the use of internal space. Although the power supply is typically mounted at the top/front of the case, the flexible mounting bracket allows for repositioning the power supply depending on the form factor. For example, if a Mini-ITX motherboard is installed instead of an ATX motherboard, the power supply can be placed in the usual position (bottom rear). This improves ventilation and configuration options at the front. Throughout the Q series, the movable I/O panel is also included in the MasterBox Q500L.