MSI MS-6739 ZIP archive of 1.46 MB. Only the brand and board number are given in its name, so whether the content is a schematic, a BIOS dump or something else remains to be seen after extraction. MSI prints the MS- code on its PCBs, usually alongside a revision marking, and both should match before you rely on the data. With a schematic, trace rails and locate components; with a BIOS image, use a flash programmer and keep a copy of the original chip read before writing.
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