Excellent choice for a pc case. I plan on getting that one for my next project.
Originally bottom mounted power supplies were installed with the fan on top. The fan pulls in warm air from the case and exhausts it out the rear of the case. However, there was another design change. Some cases with excellent ventilation, air flow, and cooling such as yours come with a an opening directly below the power supply which would allow the psu to be mounted fan side down. The concept is that with the psu fan side down, it could pull in fresh air and cool itself. There is a down side if you place the case on the floor. If you place it directly on a carpet air flow will be restricted. In addition, dust will be a problem. A few years ago I built a small inexpensive black and chrome stand to avoid those problems. I also added casters so I could move the pc easily.