In order to locate a schematic for a specific motherboard, you need to know the motherboard's manufacturer name, mode number and revision number which is stamped on the board. You cannot ask for a computer's motherboard diagram based on the computer brand name and model number.
How to Check Your Motherboard Model Number on Your Windows PC
You can use the the aforementioned link to also get the same info specs of the motherboard without opening the case by using the Command line (CMD.exe) or by downloading a GUI based software app.
However, I prefer looking at the main board for the stamped info.
How did you determine that the CMOS chip is re-configuring itself?
Are you confusing the BIOS with CMOS, which are two separate and distinct components.
If the CMOS battery on the motherboard grows weak, or becomes dead, your BIOS settings will reset each time you power off the computer.
Most CMOS batteries are replaceable; some manufacturers solder them in place.
One of the first tell tale signs of a weakening or dead CMOS battery, is having to reset the system clock.
Try changing the CMOS battery; make sure your computer is unplugged from the wall outlet (or Back-UPS); then replace the CMOS battery; plug the computer into the wall outlet (or Back-UPS); power up your computer, enter the system BIOS and configure it to your specs; remember to save the changes; warm reboot; after POST and O.S. start-up; turn off the computer normally- wait 10-20 seconds, do a cold boot to verify that the system BIOS configuration did not change.
Unless you had an electrical surge or spike that would damage the CMOS chip, in which case you might get a checksum error or.... someone is playing tricks on you by resetting the CMOS chip via its jumper; the only other culprit I can think of off hand is virus code infection to the CMOS chip.