The BitFenix Colossus Mini ITX has a the Mini-ITX form factor. Mini-ITX is even smaller than Micro-ATX, allowing PC builders the opportunity to create a low-performance, but discreet and low-power system. Using the Mini-ITX standard, the case can house motherboards and power supplies with form factors Array. The dimensions of the case itself (LxWxH) are 374mm x 250mm x 330mm.

The BitFenix Colossus Mini ITX has two expansion slots, so there is very little room for extra components, which may be a deciding factor when planning on the longevity and build type of a PC system. The case has one 5.25" drive bays, which is enough room for an optical drive but little else, though with five 3.5" drive bays, there is enough room for multiple hard drives anyway. Plus, you can mount an SSD without having to use an adapter, as the BitFenix Colossus Mini ITX has eight 2.5" drive bays. Installation of hard drives into these drive bays is made all the more easier by screwless rails that allow tool-less mounting.

Made primarily of Steel, the BitFenix Colossus Mini ITX is built to be strong and well-ventilated. Steel cases are generally fairly cheap and sturdy, but also tend to be quite heavy. Whatever your case's material, it is important to keep a consistent airflow so that heat doesn't build up inside. It is therefore advised that you make use of the available built-in case fans and fan installation sections.