Micro-ATX slim tower. ExplanationMicro-ATX slim towers are designed to be able to stand upright on desks, reducing the amount of space they require. An ATX mid-tower case would take up a considerable amount of space on a desk and are not designed to be small. While Mini-ITX towers can sit on desks, they take up more space than a Micro-ATX slim tower that is designed to stand upright. HTPC cases are design to be used with TVs and home theatre systems.