A modular, scalable and expandable (MSE) rack-based information handling system (RIHS) includes: a rack assembly having a frame that defines: a front bay chassis with height, depth and width dimensions that enable insertion of a plurality of different sizes of IT gear; and a rear bay that accommodates power and cooling components to support operation of the different sizes of IT gear. The power and cooling for the IT gear are provided from the rear bay and are separate from and independent of the IT gear installed within the front bay chassis. The rack assembly further includes a power and management chassis in which is inserted a power and management module having power and management components located thereon to provide rack-level power and management. A modular configuration of fan modules are inserted within fan receptacles within the rear bay to provide block level cooling of adjacent blocks of IT gear.