The case houses all the components, it's design and size are an important consideration, not just from an aesthetic point of view. The case has an important part to play in terms of ventilation and the overall temperature of the inside of the system. High-end cases have large dimensions and plenty of internal case fans for maximum air flow, and that's the case you should consider if opting for a high-spec SLI or Crossfire system. The more basic cases only have one internal case fan and much smaller dimensions, they are ideal for more basic systems that do not require as much heat to be dispelled.
