Circuit diagram of the Gigabyte GA-P55A-UD3 motherboard, revision 1.0B, distributed as a PDF. This ATX board uses the Intel P55 chipset for LGA1156 CPUs. The A variant added USB 3.0 and SATA 6Gb/s controllers, which this schematic should therefore cover. Use it to check the CPU and memory power stages, follow the enable and power-good chain, and find the parts around the dual BIOS chips. Verify the revision printed on the PCB first, because component values can differ between revisions.
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 @afsschematicfree. 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.