The NZXT Guardian 921 RB conforms to the ATX form factor and so can accommodate motherboards with form factors ATX and Micro-ATX.
It is made of Steel and its dimensions (LxWxH) are 522mm x 206mm x 459mm.
|Form Factor||ATX||Front Fans||1|
|Motherboard Form Factors||Front Fans Size||120mm|
|Color||Black||Top Fans Size||140mm|
|Expansion Slots||7||Side Fans||1|
|5.25″ Drive Bays||3||Side Fans Size||120mm|
|3.5″ Drive Bays||6||Rear Fans||1|
|2.5" Drive Bays||0||Rear Fans Size||120mm|
|Tool-less Rails||yes||IO Display Panel||yes|
|Length||522mm||Front USB 2.0 Slots||2|
|Width||206mm||Front USB 3.0 Slots||0|
|Maximum CPU Cooler Size||169mm||Audio IO||yes|
The NZXT Guardian 921 RB 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 522mm x 206mm x 459mm.
The NZXT Guardian 921 RB 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 space for plenty more HDDs with the six 3.5" drive bays that are also available. There are no 2.5" drive bays, though, so any SSD or laptop-sized HDD installation would require an adapter. 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 NZXT Guardian 921 RB 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.