A package includes a building block. The building block includes a device die, an interposer bonded with the device die, and a first encapsulant encapsulating the device die therein. The package further includes a second encapsulant encapsulating the building block therein, and an interconnect structure over the second encapsulant. The interconnect structure has redistribution lines electrically coupling to the device die. A power module is over the interconnect structure. The power module is electrically coupled to the building block through the interconnect structure.