There is a reason why Antec cases seem to always weigh more than their completion's. It's because they are built to a higher quality. I owned a lot of cases from all kinds of other manufactures and Antec always seemed to have a build better design and with better materials. I've own a mini p180 and a P182SE and a 800D from Corsair. I was NOT impressed with the 800D at all. Antec builds some of the highest quality cases. To be so bold, I would even say that they are better than LianLi's cases.

According to the manual, the case dimensions should only be 20.7" x 9.1" x 22.1".

Chris: I tried to keep it brief in the first post. This is still a short & semi munted version, however it is a truly complex subject. Caveat: The following only applies to tower cases.

Single fan: I did not say a single front fan, although over the years I have installed hundreds of high powered CAD & CAM or video workstations with only one front and one rear fan, and I am currently experimenting with another video editing / rendering system in a Lian Li PC6 case ? one front and one rear fan. Tricky site, they have no computer real estate at their site ? all taken up with monitors, cameras, capture gear etc. etc., while they want it quiet enough to record sound in the room! Often two lower fronts & two rear tops are needed if the machine is being hammered. My extreme machines have three in each position (plus 2 CPU fans plus a PSU fan).

Video cards: A lot also depends on the design & orientation of the components - a lot of video cards have fans which push their own hot air either downwards, which is crazy (heat rises) or through the back of the case. Some video cards actually have frontal shrouds which block the case fans from doing their job. I use oversize heatsink video cards without fans for two reasons ? they are quiet, and they are designed to allow case fans to do their job. Current system(s), 2 * gigabyte GV-R677SL-1GD silent cell graphic cards (dual slot full length & height cards - the fastest cards I could get at the time without fans) which are driving 5 * 1080P monitors ? I am not a shoot'em up gamer, this is for video editing and rendering, ERPS reporting, research and writing. During initial (brutal) system testing, they stayed well below 50C (Celsius) in controlled 30C ambient. During my actual use their rear heatsinks are always warm when running hard, however they haven't ever reached close to that temp again (25C ambient helps). Another under-appreciated issue is the necessity for vented backplanes above and below the video cards, and preferably vents in the rear of the case to the left of the video cards as well.
In short ? futz the orientation of your components or vents up, and your system may well need an ever increasing number of fans running in all directions at ever increasing speeds to keep it cooler (and always relatively noisier).