Since the models tested today come with just a single 80mm fan each, you will want to add some cooling into the rig. With so many to choose from on the market, you will be able to find something that fits into your performance/noise realm. Just make sure to put at least one fan in the front and one in the rear, but filling up all openings is always a better choice for the best possible cooling.
That said, I decided to break the rules and test both cases with just the single side fan installed since I already know that some folks will run it in this manner. Then I ran some system-intensive utilities to see how the internals handled the heat. The results ended up surprising me a bit, but considering the aluminum construction it shouldn't have.
The CS-528 model ran at a reasonably comfortable 36 degrees Celsius. Considering that there is only the one fan installed into the side panel and no other air circulation inside, this is really a good temperature. Adding a couple of slow moving (i.e. quiet) fans to the mix dropped the temperatures by another two degrees. As a comparison, the aluminum PC-60 enclosure from Lian-Li keeps the system at 31.5 degrees Celsius under the same conditions; but then the Lian-Li also costs about 2-3 times as much as our Enermax models.
The CS-718 didn't fare quite so well. Remember earlier on when I noticed that there weren't any air vents on the front of the bezel? It ended up costing the system temperature 2 degrees. With just the side fan going we ended up with a result of 38 degrees Celsius and the added slow moving fans brought it down to 36 degrees; the same temperature that the CS-528 managed with just the side fan going. So while it didn't make a large a difference as you might have thought, you will have to put up with marginally higher temperatures with the CS-718 Series case.