They're not really "Scratches" and thier not even deep. All it is is scraping off the gold connection between the bridges. And you don't need to do that, because if you want to unlock the multiplier you CLOSE all the bridges which means you make them all connect.
Yes ther is a way to overclock without touching it. Only with ABit KT7 can you really overclock without touching anything inside the case. Go into the BIOS and change the FSB from there to overclock (If you didn't unlock multiplier).
But, overclocking with the FSB kinda sucks and unlocking the multiplier is the best way.