Natural alcohol or 91% isopropyl alcohol would be best. Alcohol evaporates very quickly and cuts through thermal grease like nothing. Not sure about thermal(wax) pads though.
Your alcohol is probaly 70% isopropyl (30% water). It will work, but it won't be quite as clean. Doesn't evaporate as quickly either, but that's not a big issue. Just make sure there is no voltage running to your CPU when you clean it ;').
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