A 418 KB zip archive tied to the P5GC-MX-1333 desktop board, the 1333 suffix in this naming usually marking the variant that supports a 1333 MHz front-side bus. The file name does not say what is inside, so expect anything from a BIOS dump to a service document until the archive is opened. Technicians typically use such packages to recover a board with corrupted firmware via an external programmer; verify the silkscreen model and revision first and keep a backup of the existing chip before flashing.
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 @laptopchiplevelrepair. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.