Semiconductor packages and package assemblies having active dies and external die mounts on a silicon wafer, and methods of fabricating such semiconductor packages and package assemblies, are described. In an example, a semiconductor package assembly includes a semiconductor package having an active die attached to a silicon wafer by a first solder bump. A second solder bump is on the silicon wafer laterally outward from the active die to provide a mount for an external die. An epoxy layer may surround the active die and cover the silicon wafer. A hole may extend through the epoxy layer above the second solder bump to expose the second solder bump through the hole. Accordingly, an external memory die can be connected directly to the second solder bump on the silicon wafer through the hole.