Raganarokblade666

smart switch was my favorite!
ty guys!

Actually I meant CH3OH. Ethyl alcohol being the commercial name. Ethanol being what it actually is. You can use brand new ethanol easily, as it probably will be pretty close to that 96% purity they quote. It isn't advised to leave it sitting on a shelf for a week however. Commercial ethanol is quite often derived from a variety of sources (whatever is cheapest to produce), the big one in the news atm is corn (maize) where a lot of the fuel additive is coming from. Very rarely is it synthesized.
 
Isopropyl alcohol on the other hand is synthesized. The only biological component it includes is propene, which ceased living a few million years ago.
 
Basicly what 'm saying is that some impurity will always be found in any process. Quite often in ethanol it's the ketones, and esters which give drinking alcohol it's flavour. In isopropyl alcohol it's quite often a bit of sulfur.  Both reactions will absorb moisture from the atmosphere if left on a shelf somewhere. the amounts are minimal at production, they're usually minimal at use.
 
I prefer isopropyl. mainly as queek stated, it's cheap, and readily available in sufficient purity. Ethanol is a little harder to come by in sufficient purity unless you have access to a chemical warehouse.
 
BTW, while you can use it, common rubbing alcohol only has to be 70% pure reach standards, and can be either ethyl alcohol, or isopropyl depending on the manufacturer.

Yes what sgloux3470 said.  Lots of misinformation.  Isopropyl is preferable and cheap for this application, but as long as you mean ethyl alcohol and not "vodka", that can be used as well.  Just allow for a few minutes for it to properly dry before reapplying new paste.  
 
When most people say "ethanol" on this forum, they're actually talking about vodka, which you should not use.

So much misinformation in one thread.
 
Ethanol is safe to use, provided that you are using concentrated ethanol (i.e rubbing alcohol) and not using vodka or whatever.  
 
Ethanol is slightly less volatile than isopropyl alcohol, but the difference between the two is trivial.  Dampen a non-fibrous cloth (coffee filters work best, paper towel works second best) and wipe it down.  By the time you finish wiping it will be evaporated completely.  If you want to be really safe, give it 2-3 minutes before putting the new heatsink on.

The problem with ethyl alcohol isn't so much the fact that it isn't as volatile, as what it leaves behind. Ethanol, is basically the stuff you drink, and all those ketones and impurities get left behind. Add in the fact that it impossible to maintain ethanol at a high purity without specialist chemicals (it leaches moisture from the air), and you're left with a compund that you really don't want left on your cpu.

Thx to everyone, yeah i dont want my pc to be on fire!

No you can go to your drug store and pick up a bottle of rubbing Alcohol 

Check your local drug store, rubbing alcohol is a good choice.
Be sure to clean off any little fibers left by the paper towel if you decide to use paper towel!

You can use a barely damp paper towel if you can't find isopropyl alcohol, ethyl alcohol shouldn't be used since it may leave a residue. 

Yeah, don't use Ethyl Alcohol, you'll probably put your computer on fire. As far as I remember from chemistry, it doesn't evaporate as fast as isopropyl, so go to the drug store (i.e. wallgreens, cvs, even a grocery store would have it) and try that. Wallmart and Target probably wouldn't have it sooo, there's that. Remember 100% isopropyl dries faster than 70%!