Gigabyte GA-965P-S3 motherboard schematic in PDF, where the 33 tag most likely marks revision 3.3. The board is an Intel P965 LGA775 ATX design. Its pages lay out the CPU core regulator, DDR2 supply, chipset and standby rails, clock generator and BIOS wiring. These are useful for checking voltages at known points, tracing a short to the faulty component or confirming why the board will not power on. Verify the revision number printed on the PCB before depending on part values or layout details.
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 @schematicslaptop. 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.