CPU Thermal Goop/Grease/Compound

letdown427

Golden Member
Jan 3, 2006
1,594
1
0
OK, i've noticed quite a few people asking about it, and I myself didn't know when I first came to stick on a new heatsink, so here goes. Hopefully this will help out those people who aren't sure how much goop/grease/compound to put on.

REMOVAL:

Before applying your new goop/grease/compound/toothpaste , you may need to remove any thermal pads or other interface material from the heatsink/ CPU's IHS (metal case over the core).

Thermal pads can be scraped off with a plastic tool that will not scratch the bottom then the remnants can be removed with a xylene based cleaner, (Goof Off and some carburetor cleaners) acetone, mineral spirits, high-purity isopropyl alcohol or Akasa TIM-Clean.
Often, thermal pads are made with paraffin wax that melts once it gets hot. When it melts, it will fill in the microscopic valleys in the heatsink with wax. To minimize the permanent contamination of the mounting surface with wax, the thermal pad should be removed before it is used and melted. Never use heat or hot water to remove the pad, the heat will melt the wax into the heatsink, which is bad.


The bulk of greases/goops/compounds can be removed with whatever you deem fit, cotton buds, a plastic tool of sorts, and then the remnants removed with the same ingredients as listed above, alcohols, acetone etc.

***

The recommended cleaners are:

CPU Core:

Use high-purity isopropyl alcohol, acetone, Akasa TIM-Clean and a bit of careful rubbing.
I tend to use some brake disc cleaner I've got around the house, worked a treat on my GPU.
Do not use nail polish remover as it contains fragrance oils and other contaminants.
(If you use acetone, do a final cleaning with isopropyl alcohol.)

Heatsink:

Use xylene based products (Goof Off, some carburetor cleaners and many brake cleaners), acetone or mineral spirits.

Never use any oil or petroleum based cleaners (WD-40, citrus oil based cleaners and many automotive degreasers) on the base of a heatsink. The oil, which is engineered to not evaporate, will fill in the microscopic valleys in the metal and significantly reduce the effectiveness of any subsequently applied thermal compound.

***

Do your best to ensure the surfaces are dry and free from dust, to ensure the cleanest, and therefore best, contact possible.




APPLICATION:

When applying it, it's worth noting that the actual core is only in the very centre of the metal CPU heatspreader. Therefore, it isn't worth smearing thermal compound over the whole face, as the core isn't anywhere near the edges.

Thermal compound is basically not a great thermal transfer agent. So why do you use it? Well, you can't get the HS and the cpu to contact each other uniformly all over. There WILL be microscopic gaps, and in these gaps, will be air. It is because air is an even worse thermal transfer agent than thermal compounds that they are used. The compound is meant to fill in these microscopic gaps, and ideally no more.

So, you want the layer to be as thin as possible. Having it thick will inhibit thermal transfer, and raise temperatures(ignoring how much, fact is, it WILL raise them by something)

If you've sloshed it on thick, squished down your HS and it's oozing out the sides, that is bad. Well, some thermal compounds aren't that electrically conductive, but some (like toothpaste) are, and so it's advisable to plant yourself firmly on the safe side, and clear it up.



So How Big A Blob?

http://www.arcticsilver.com/images/p4_as_dab1.jpg

That's a picture from the artic silver guide that basically shows how much you need.

P4- About the size of an uncooked grain of short-grain white rice or 1/2 of a BB.

Athlon64- About the size of one and a half uncooked grains of short-grain white rice or 3/4 of a BB.

Thats from the arctic silver instructions below.

So, along with that small blob in the middle, they also state it's advisable to lower the heatsink straight down onto the CPU, and give it a slight twist a few degrees each way, apparently:

"this method minimizes the possibility of air bubbles and voids in the thermal interface between the heat spreader and the heatsink. Since the vast majority of the heat from the core travels directly through the heat spreader, it is more important to have a good interface directly above the actual CPU core than it is to have the heat spreader covered with compound from corner to corner."

Hopefully this'll help those of us that are new to thermal compound application, if anyone has any extra contributions or essential reading, feel free to add to the thread.



Essential reading:

http://www.arcticsilver.com/arctic_silver_instructions.htm

http://www.techpowerup.com/articles/overclocking/134



The science bit:

http://www.heatsink-guide.com/content.php?content=compound.shtml



So what do AMD say?

http://139.95.253.213/SRVS/CGI-BIN/WEBC...0251604970,K=9383,Sxi=5,Case=obj(3864)



An interesting little bit of additional reading.

http://www.thetechzone.com/reviews/roundup/thermal_compound/index.shtml

Round-up of compounds. Arctic Silver wins out. Quite well actually.

http://www.dansdata.com/goop.htm

Maybe it isn't awesomely accurate, but the fact is, for the short term, toothpaste/vegimite/water are better than arctic silver. lol. honestly.

 

imported_Knoxville

Junior Member
Jan 24, 2006
1
0
0
Excellent, thanks man. I got this wrong last time and spread it all around the corners like a complete and utter idiot.

Sticky this.
 

lopri

Elite Member
Jul 27, 2002
13,209
594
126
I just use whatever I have at the time. A LOT more than what the picture shows. heh.. Also, 99% alcohol... well, if I have it then great, but often times I don't have it and many drugstores don't carry it. (They usually have 70~80% ones) I just use CK One, Kenzo, etc. depending on my mood. It's been working well and smells good, too. :D
 

Doctorweir

Golden Member
Sep 20, 2000
1,689
0
0
Originally posted by: lopri
I just use whatever I have at the time. A LOT more than what the picture shows. heh.. Also, 99% alcohol... well, if I have it then great, but often times I don't have it and many drugstores don't carry it. (They usually have 70~80% ones) I just use CK One, Kenzo, etc. depending on my mood. It's been working well and smells good, too. :D
Lol, so your CPU does not smell bad when sweating from the high temps... ;)
 

mphartzheim

Member
Jan 25, 2006
93
0
61
Bump this for a sticky... I'm about to build my first rig in a few years and I woulda gooped the entire CPU with compound had I not read this.
 

wlv

Junior Member
Sep 1, 2005
23
0
0
great piece of work there.

would be nice if u could add a little on removing paste/compound/grease etc from a heatsink/cpu as well.
 

Howard

Lifer
Oct 14, 1999
47,989
10
81
I'm sorry, but what kind of link is that?

EDIT: I hate when silicone is confused with silicon.
 

Yakomo

Senior member
Dec 8, 1999
269
0
76
Very informative post, now I realize that making the area between my hsf and cpu look like a smores is not a good idea. Definately sticky this!