I used a Corsair Carbide 200R case in a recent HTPC build. It was the right size, and seems like a well-designed and well-constructed case at its moderate price. However, in addition to the front intake, rear exhaust, and bottom-mounted power supply fans, there are five more unused 120/140 fan mounts: two on top, one on the bottom, and two more on the side. This seems like much more cooling than needed for this modest build: Core i3-3225 (55W), one SSD, one HDD, two optical drives, a flash card reader, and two sticks of 8 GB DDR3. Using the stock CPU cooler, Intel 4000 graphics and integrated sound.
It seems to me that airflow would be improved by covering (blocking) those five extra fan grills. This might also help keep dust bunnies from crawling into the case. Is this correct, or is it no big deal?