PC Bios/CMOS query

Does anyone know if the BIOS binary file for flashing a BIOS actually also carries information for the CMOS?

THe reason for asking is, I was trying to test the theory that Nforce2 MBs actually store some information that would normally be in the CMOS in the BIOS instead (ie it actually partially flashes the BIOS when for example the FSB is changed).
I extracted the BIOS from my 8RDA+ board using the awdflash utility and compared it to the original BIOS I had loaded using a binary file compare. There were several areas of difference which I confirmed with a Hex editor.
I then changed the FSB on my machine and re-extracted the BIOS, compared this with the previously extracted BIOS and again it was different in several areas but not as many as the comparison with the original.
There did however seem to be too may differences and it made me wonder if BIOS BIN files do carry CMOS info in them so that if you extract the BIOS you also copy significant amounts of your current CMOS settings.
So would you expect a saved BIOS to be the same as the original BIOS or not?