PDF schematic for the MSI MS-7782 motherboard, delivered inside a RAR archive of about 1.10 MB. The file name gives no revision, so look at the title block on the diagram pages and compare it to the version marked on the board itself. With the schematic open in a PDF viewer, a technician can follow the standby and main power rails, read the expected voltages at regulators, and see which signals gate the power-on sequence. The MS-7xxx code is MSI's internal desktop board identifier rather than a retail model name.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.