MSI MS-7399 motherboard schematic, revision 1.1, in PDF format at about 1 MB. Beyond board number and revision the name gives no further details. The MS-7xxx numbering is MSI's scheme for its desktop mainboards. Engineers use these sheets to trace voltage rails from the ATX input through the regulators, check power-good and reset lines, and identify components around a short. Many revisions of the MS-7399 are listed, so match the revision on the PCB to 1.1 before relying on designators.
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 @pepeelectronica. 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.