Embodiments include semiconductor packages and methods to form the semiconductor packages. A semiconductor package includes a plurality of first dies on a substrate, an encapsulation layer over the first dies and the substrate, an interface layer over the first dies and the encapsulation layer, and a passive heat spreader on the interface layer, wherein the interface layer thermally couples the first dies to the passive heat spreader. The passive heat spreader includes a silicon (Si) or a silicon carbide (SiC). The interface layer includes a silicon nitride (SiN) material, a silicon monoxide (SiO) material, a silicon carbon nitride (SiCN) material, or a thermal adhesive material. The semiconductor package may include a plurality of second dies and the substrate on a package substrate, a thermal interface material (TIM) over the second dies, the passive heat spreader, and the package substrate, and a heat spreader over the TIM and the package substrate.