RAR archive of 156 KB labelled P8B75-V with version 2.04, which fits the naming of ASUS Intel B75 chipset desktop boards; the number most likely denotes the PCB revision covered by the enclosed file. The contents are not listed, but files this size are commonly boardviews. Extract it and open boardview data in OpenBoardView or a compatible viewer to locate parts, follow nets and find test points. Check the revision silkscreened on your board, since separate 1.00, 2.00 and 2.01 versions of this name also exist.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.