The Antec Performance II SX835II has a the ATX form factor. ATX is the most ubiquitous of case standards, providing the largest array of compatible hardware on the market. Using the ATX standard, the case can house motherboards and power supplies with form factors ATX and Micro-ATX. The dimensions of the case itself (LxWxH) are 472mm x 206mm x 440mm.

The Antec Performance II SX835II has seven expansion slots, so there is plenty of 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 three 5.25" drive bays, which is enough to house an optical drive and a couple of hard drives, while still having a couple of extra free hard drives with the two 3.5" drive bays that are also available. To mount an SSD you would require an adapter, however, as there are no 2.5" drive bays.

Made primarily of Steel, the Antec Performance II SX835II 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.