Archive of roughly 698 KB labelled with the ASUS P9X79 PRO motherboard name, packed as RAR. The file name states neither revision nor content type, so check what it holds after extraction. Such packages usually contain boardview or schematic material, helpful for locating parts, measuring VRM output and memory voltages, following power-good signals and finding a shorted component on the board. Since PCB revisions may differ in layout, confirm the revision printed on your board matches the documentation inside.
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 @boardview. 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.