Zip package of 1.49 MB for the Gigabyte GA-EG31M-S2 motherboard, an Intel G31 based micro-ATX board by its name. The file name gives no revision or detail about what is inside, so unpack it to see whether it holds a schematic, boardview data or a BIOS dump. Schematics of this board family are handy for tracing standby voltages, VRM control, the chipset core supply and the clock generator when a board will not start. Check the revision printed on the PCB against the file, and back up any SPI or LPC flash contents before writing a new image.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.