Techniques and mechanisms for providing interconnected circuitry of an integrated circuit (IC) die stack. In an embodiment, first integrated circuitry of a first IC die is configured to couple, via a first interconnects of the first IC die, to second integrated circuitry of a second IC die. When the first IC die and the second IC die are coupled to one another, second interconnects of the first IC die are further coupled to the second integrated circuitry, wherein the second interconnects are coupled to each of two opposite sides of the first IC die. In another embodiment, the second integrated circuitry includes processor logic, and the first integrated circuitry is configured to cache data for access by the processor logic. In another embodiment, the first integrated circuitry includes a power delivery circuit and an on-package input-output interface to cache data for access by the processor logic at higher bandwidth with lower power consumption.