It depends on the nature of usage; if you are a gamer or graphics designer, you need to get at least three fans to keep components cool and fresh. A fan for air intake is necessary on the front panel, and one exhaust looks good on the back panel. However, you can have results with a couple of fans, but having three or more is the ideal deal to go with. So, it is better to invest in tuple fan count, not in less than two.