The invention provides a semiconductor package assembly. The semiconductor package assembly includes a first semiconductor package and a second semiconductor package stacked on the first semiconductor package. The first semiconductor package includes a first redistribution layer (RDL) structure. A first semiconductor die is coupled to the first RDL structure. A first molding compound surrounds the first semiconductor die, and is in contact with the RDL structure and the first semiconductor die. The second semiconductor package includes a second redistribution layer (RDL) structure. A first dynamic random access memory (DRAM) die without through silicon via (TSV) interconnects formed passing therethrough is coupled to the second RDL structure.