Hello, I have a Xigmatek Dark Knight that I bought from the Egg about a month ago. Recently I noticed that there was some dried stuff on the top fin of the heatsink, so I rubbed it off with rubbing alcohol (91%) and wiped it with some lint-free cloth. However, when I looked at the heatsink about a week later, I noticed that there were multicolored patches of residue on the fin. I have tried water, 97% rubbing alcohol, and spit(lol) but the blotches come back after a few hours. Have I gone too far and messed up the black paint of the aluminum or can this be fixed? Thanks.