Inside the Corsair Carbide Series 400R
Both panels are attached to the chassis using black thumbscrews. These thumbscrews stay permanently attached to the side panels, so there is no way you can lose them. The motherboard tray has a huge hole for you to access the backplate of the CPU cooler without having to remove the motherboard from the case, several holes protected with rubber covers for you to route cables behind it, and a few metallic clips for you to fasten cables using cable ties.
In Figure 13, you have another overall look inside the case. Expansion cards are fastened using black thumbscrews. The 400R supports video cards up to 12.4” (316 mm) long.
The power supply is installed at the bottom of the case. Note that it can be installed with either its bottom fan facing up or facing down, so you can decide if you want the fan of your power supply pulling air from inside the case or from outside of it.
If you install a power supply up to 6.9” (175 mm) deep, you can install a 120 mm or 140 mm fan on the bottom panel. With a power supply up to 7.3” (185 mm) deep, you still can install a 120 mm fan. But if you have a power supply deeper than that, you won’t be able to install a fan on the bottom panel.
As shown before, the bottom panel has an air filter for the power supply fan and for this optional fan.