RAR archive of 147 KB for the P8B75-V desktop motherboard, revision 1.00, the earliest version among files with this name; the model follows ASUS naming for Intel B75 chipset boards. The name does not say what is enclosed, but a boardview is the likely content at this size. Extract it and open the layout in a boardview viewer to identify components and nets, trace rails from the VRM and check suspected shorts. Confirm the PCB revision silkscreen reads 1.00 before trusting component positions.
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.