For future reference, keep this product in mind.
Zalman Thermal Material Remover and Surface Purifier. (PIC Below) It's relatively in expensive and it's 1000 times better the alcohol.
It quickly emulsifies and dissolves the existing thermal grease or pad from the CPU and/or heatsink so that it can easily be removed with a clean cloth or paper towel. A few drops of ArctiClean 2 Thermal Surface Purifier and some gentle wiping then removes the remaining residue and inhibits flash corrosion on copper or aluminum.
The ingredients in the remover are all natural. They actually use citrus oils, that instantly break down the thermal material. The purifier makes the surfaces clean enough to eat off of.
You can go from nasty surfaces to clean as a whistle in under a 30 seconds. It's that good.