Archive labelled for the Dell 745, most likely the OptiPlex 745 desktop, though the name gives only the model number and no board revision or contents list. The RAR file is 968 KB, a size consistent with a BIOS dump of an SPI flash. Technicians use such files to restore a system board that will not POST after a failed update. Extract it, look for any readme, and compare against the chip on your board. Save the original chip contents with a programmer before writing anything.
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 @hrtechno. 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.