I am about to attach a new CPU fan. I wondered whether it was better to apply thermal paste to the fan or the CPU, so I looked it up. The first source I found (https://www.intel.com/content/www/us...mal-paste.html) says apply it to the CPU, so I'll do that; but I wonder if it really makes a difference which surface the paste spreads from.

(If you ask why I don't just try pasting the fan and seeing how it works, I don't care to waste any paste or clean it off afterwards.)

i put it to cpu, it were really easy thing to swap a cooler.
just dont put it too much.

1 members found this post helpful.

There's probably no functional difference, but the risk is that you could rub the bottom of the cooler on a wire or some other component on the way in. This could lead to a big mess which you will need to clean with spirits of some sort because thermal paste is quite greasy. It makes a lot more sense to put it directly into the CPU.

I did put paste on the CPU; but accidentally ended up also trying it on the fan. I conclude that in addition to what you said, the fan surface is harder to clean paste from if necessary. With my poor coordination, I apparently got some paste on the fan before inserting it--don't ask how. It took a little more effort to clean it off, and it smeared more easily.

I think the CPU heatsink surface is easier to clean. I had to clean the old paste off from the first fan that this fan is a replacement for. I sprayed some household cleanser on a cloth, and then wiped the CPU easily in one or two passes.

Remember, less paste is better. Chip surface in direct contact with cooler is the ideal, paste is only to fill possible imperfectness. Very much like you use putty to level the surface before painting. What really would be the best is to apply small amount on both, then use some blade to remove excess while making sure the whole surface is "treated", then install the heatsink. Well, that's what I do.

1 members found this post helpful.

Ideally thermal paste gets applied to the surface that will get hottest which is then firmly and evenly attached to the biggest heatsink you can manage It's actually more thermally efficient if the surfaces are not mirror smooth, because that unevenness increases the surface area. But they should not be warped.

That said, 99.9% of surfaces in electronics are mirror smooth.

1 members found this post helpful.

Hi,

Preparation is very important. You need to be sure to have both surfaces clean before attempting thermal paste application. I use plastic razor blades to mechanically remove old paste. I then use microfiber cloth and isopropyl alcohol to wipe both surfaces. Be sure both surfaces are clear of old materials. If you do not have a microfiber cloth then use something that is lint-less so you will not leave any contaminants.

If you use tubed thermal paste that you might have laying around then be sure to knead the tube so to mix the thermal paste. Even if you use plastic packets of thermal paste you should knead the package to thoroughly mix the paste because over time some separation can occur.

I apply the paste to the cleaned surface of the CPU then be sure too attach the heat sink with pressure evenly. Do not be tempted to twist the heat sink thinking this will aid in dispersion, it will only create uneven application. Securely attach the screws or other attachment device.

I monitor my temperatures to see if temps are in range for the device.

Hope this helps!

1 members found this post helpful.

Helpful, thank you. You cut the paste off with a razor blade? Is that necessary because the paste is too hardened to just wipe off?

Well, I guess I applied my paste acceptably, because I started running the computer and the temperature hasn't exceeded much above 90 F, especially since I bothered to plug in the chassis fan in addition to the CPU fan.

i have seen / heard about using razor for that purpose also.

and yea, ppl use it because its hardened.

1 members found this post helpful.

Hi,

Yes, the plastic razor blade is useful when removing dried paste or even semi-dried paste. I use the plastic blades so as not to scratch the surfaces. It all depends on the age of the paste along with usage as to the status of the dried paste.

1 members found this post helpful.

They did or still do make a sort of tape type conductive material. I got it with a cooler one time.

50% of the time it's better to put on cpu first. 50% of the time it's better to put on cooler first. 100% of the time it makes no difference.

1 members found this post helpful.

Hi,

I really do not like thermal tape. It can be pain sometimes to remove a heat sink from the cpu that has thermal tape applied. Never had a problem with paste when a heat sink needs to be removed.

1 members found this post helpful.

There is the other issue that thermal paste dries over time. At this point, if the item is knocked, the paste can crack and disappear at the edges, leading to local thermal stresses. Thermal pads are a niusance, but they avoid that trap.

Silicon grease isn't a bad substitute for thermal paste, not as efficient, but longer lived.

1 members found this post helpful.

i saw one test that tested different substances like thermal paste / toothpaste / ketchup / mustard.

there were no differences on cpu temperatures.

1 members found this post helpful.

What?! Surely the test had an error somewhere.