Intel D915GAV desktop motherboard archive, code name Avalon, marked FAB D and Rev 4.0, in RAR format at 1.2 MB. The 915 designation points to the Intel 915 chipset family. Contents are not stated; likely schematics or service documentation for this board. A technician can use such material to trace VRM and standby rails, check the power-on circuit and locate components around the memory and CPU sockets. Check that the FAB revision printed on the PCB matches before relying on values.
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.