[Solved] Removing Thermal Paste

CPU thermal compound requires an organic (read: hydrocarbon-based) solvent to dissolve. The less water the solvents have, the better, as water is inorganic and will not dissolve thermal compound. Hydrocarbon and alcohol-based solvents with 10-15% or less water by volume work well. Apply the solvent to something lint-free like a cloth or coffee filter and then rub off the thermal compound. A good solvent will make the thermal paste dissolve quickly and rub off very easily.

My favorite solvent for removing thermal compound is 91% rubbing alcohol (9% water.) It stinks a lot less than most other organic solvents, it works very well, and a pint of it costs about a dollar at most drugstores. A pint will be enough to remove thermal paste from dozens and dozens of heatsinks. Most running alcohol is 71% alcohol/29% water and does not remove thermal paste very well, so specifically look for the 91% stuff.

Other solvents I've used are:
- Goof-Off. This is made of benzene derivatives (toluene, xylene) and smells to high heaven. You do not want to use this indoors and you do not want to put your used cloth/rag soaked in the stuff in the trash indoors either. It comes in metal cans at the hardware store and costs several dollars for a 8 or 16-ounce container. It works very well.
- Denatured alcohol, which is 90-95% ethanol, a few percent water, and a few percent gasoline or methanol to make the mixture non-potable (else you would have to pay beverage alcohol tax on it and it would be very expensive.) This works very well and has very little odor. The only downside to using denatured alcohol is that it generally comes in quart or gallon cans and you'll never use all of that for removing thermal grease unless you plan on removing hundreds or thousands of heatsinks' worth of grease.

Other stuff that should in theory work, but I've never tried
- Mineral spirits/paint thinner. Cheap, widely available, but very stinky.
- E85 motor fuel. Basically the same thing as denatured alcohol and cheaper, but hard to buy in small quantities.
- Straight toluene or xylene. These will work as they are what make up Goof-Off. You can buy them in the paint aisle at a hardware store. Goof-Off comes in smaller containers, so that's why I have used Goof-Off instead of these chemicals. These are also very stinky.
- Diethyl or methylethyl ether. This is the main component in engine starter fluid and is a highly-volatile liquid. It stinks to high heaven, forms an extremely flammable vapor cloud in the air, and you sometimes have trouble buying it since it is a component in methamphetamine production. It is a very effective organic solvent, so it should work well for dissolving thermal compound.