MSI MS-7551 material packed into a 2.61 MB ZIP archive. No revision appears in the name and the contents are not described, so open it with any ZIP utility and check what is included. MSI desktop boards carry an MS-7xxx code and a revision label on the PCB, and that marking is what decides whether documentation applies. Since this set does not specify a revision, compare layout and component markings with your board before using it to trace rails or locate faults.
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 @IT_SERVICE_WORLD. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip