A dual-model memory interface of a computing system is provided, configurable to present memory interfaces having differently-graded bandwidth capacity to different processors of the computing system. A mode switch controller of the memory interface controller, based on at least an arbitration rule written to a configuration register, switches the memory interface controller between a narrow-band mode and a wide-band mode. In each mode, the memory interface controller disables either a plurality of narrow-band memory interfaces of the memory interface controller according to a first bus standard, or a wide-band memory interface of the memory interface controller according to a second bus standard. The memory interface controller virtualizes a plurality of system memory units of the computing system as a virtual wide-band memory unit according to the second bus standard, or virtualizes a system memory unit of the computing system as a virtual narrow-band memory unit according to the first bus standard.