A scalable computer system includes a reconfigurable chassis module, plural hardware units and one or more inter-plane. The chassis module has plural modular units for configuring the hardware units therein respectively. Each of the modular units has dedicated framework to attach the inter-plane or dedicated fans. The inter-plane is to connect with the separated hardware units between the modular units. Each of the modular units is equipped with compatible male and female joints to engage with each other. Certain fastening assemblies may be applied to secure male-male or female-female joints, thereby enabling the modular units to be front-to-back and/or side-by-side connections.