MSI schematic in PDF covering MS-7A78, with the name also listing MS-7A781, likely a sub-variant of the same design. At 7.25 MB it is a sizable document. Desktop board technicians use pages like these to follow VRM phases, memory and chipset power, USB and audio routing, and the power-on sequence when a board stays dead. Check which code and revision appear on the PCB before relying on part numbers, as variants may populate components differently. Any PDF reader with search will open it.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @afsschematicfree. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.