Datasheet for the ON Semiconductor NCP81218, a fairly large 2.83 MB PDF. NCP812xx parts are multiphase controllers used in CPU and GPU core voltage regulators. The document is the reference for pin functions, enable and power-good logic, phase configuration and the serial VID interface, all useful when a core rail fails to start or a phase stays dead. Measure supply and enable pins against the values in the sheet, and check the top marking before assuming the chip on the board is this exact part.
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 @ic_mosfet_pdf_datasheets. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.