If you look at the Silent Base 800, you might mistake it for an eATX or larger type case. The reason for this is because its top and bottom sides are actually plastic additions over the steel frame - adding about 18 cm to its overall height.
These aren't just for fluff - they're added to enable dedicated air-flow space. Thankfully, the ABS plastic used seems to be of proper quality and doesn't have a cheap feel to the touch.
Side panels are coated in sound-isolating material (for the right side there's a fan-spot right in the middle) - different from the one used by Fractal Design or Silverstone.
The internal layout is as expected. It features 4 large rubber grommets of the same color as the rubber accents. The dedicated motherboard tray uses bumps instead of traditional spacers to be kept in place.
Since in principle this is a mid-tower case, there are seven expansion slots, and a bottom PSU bay. Turning it around, you find there is about 22mm worth of space for cable management, which should be enough - though sound-dampening material and the fan-mounting bracket would also eat up some of the available room.
On the motherboard tray, be quiet! included 2x SSD / 2.5" drive frames. Each of these is held in place via a thumbscrew.
In terms of clearance, the case allows the installation of up 170mm tall CPU coolers or liquid cooling heatsinks as large as 280mm (at the top). For the graphics card, you can insert one measuring up to 290mm in length (or 400mm if you remove the drive cages). The PSU is bottom mounted, and there's ample space for an ATX sized one (up to 290mm.
For my test-bench, I prepared an ATX motherboard, an Intel i5 processor with a 240mm Fractal Design Kelvin S24 liquid solution. The GPU in use is a Sapphire GTX 280X - not the most powerful graphics card at my disposal, but clearly one of the most supersized.
For storage, I attached an SSD drive to the motherboard-tray rear, and a 3.5" mechanical drive in one of the cages.
The ample space for cable management allowed me to deftly hide out the excess wiring. The rubber grommets surrounding the MOBO provided easy access for pretty much every cable to reach its target.
Lastly, for the liquid-cooler, I had to remove the top-plastic shell and install the radiator onto the steel frame. This proved to be a bit of a hassle - since the plastic top wasn't bolted down - but clipped on with plastic holders. There was also a detach order. First the front has to be removed before having access to the top & bottom units.