Time to take a closer look at the chassis. First off, to remove the front bezel you need to just pull a bit harder, and it pops out. Be careful though, the wiring goes through the frame, and yanking it open, might cause something to snap. In fact, the first I took off the cover, I pulled too hard and the blue power LED came out of its slot.
Inside the bezel, there's a dedicated slot for the optical drive, as well a plastic cage where you can add 2xSSDs.
Taking out every available panel (top / left / right), and I am left with a nicely built, aluminum cage and several white accents. This is where that Swiss-knife nature comes into play. If you're looking for water-cooling, the case has several designated spots, including mounts for a 240mm (60mm thick with fans) radiator in the right and left chamber (the one in the left chamber prevents the use of a fan at the top). Topside there's enough space for a 240/280mm radiator location (130mm thick) in the right chamber if the HDD drive bays are removed, and for a 240mm radiator in the left chamber. Note: For the last one mentioned, you need low-profile memory (48mm tall).
Though there are 10x120mm fan slots scattered across 804's frame, I honestly believe the case was designed with negative airflow in mind, since one of the filters was positioned right under the power supply, and another one sitting at the bottom, where you can have drive-mounts for either 2.5" or 3.5" SSD / HDD. Speaking of filters, there are 2 in front, and 2 at the bottom. The top-cover has a thick layer of noise dampening foam (which you can't really remove if you want to).
Installation & Management
The chassis is segregated in two chambers, one for the motherboard & video-card, the other for PSU & HDDs. If I'd hazard a guess, I'd say Fractal Design opted to create thermal-zones and move the HDDs away from the CPU.
On one side you can add the mATX motherboard, which should take up almost the entire height of the case, those two additional HDDs at the bottom (if you decide to use 'em there). Overall, the design is akin to other cube-shaped cases, though the cable management options are relatively bizzarre, with one large space to the side, and only a cut-out down.
The motherboard tray features a very large cooler access hole. To install the MOBO you have to add all but the low-left standoff, which seems to be attached to the frame.
The other compartment offers more room for fans up front, 2xHDD cages that use thumbscrews to be secured, and an additional 120mm fan at the back. Where the PSU is supposed to be located, there are several rubber pads raising the PSU off the floor. There are also 2xvelcro straps to keep the wiring from the PSU in order (of course, not in my case).