Interior
Removing the left side panel reveals the back of the motherboard tray. As this is a reverse-mount motherboard, the business end of the chassis is the right panel.
Removing the right side panel (the one with the SSD trays and front panel ports, we can see what we’re gonna be working with. The BitFenix Colossus mATX is quite roomy without anything inside. That’ll change though once we get the components inside. We can see a single 120mm is included to vent air out of the case from the bottom-rear.
A large 230mm vent is present although you won’t be able to use it since the PSU will occupy this space primarily. Speaking of PSU, the PSU is mounted via a bracket that screws into place from the bottom of the PSU. An extension cable routes through the bottom to the rear of the case for cosmetic purposes. A single 120mm is located on the bottom of the Colossus mATX as an out-of-the-box inclusion but you can use a large 230mm fan at the bottom should you not be using a radiator or HDDs in that area.