Applying Thermal Paste. Dot Method VS Spread Method

[Psycho92]

So my new Intel i7 2600k is going to be turning up next week. I have done a bit of research into different methods of how to apply the paste and it seems there are many different techniques. Some people say this way is correct while others just flame them and say its wrong.. I am confused now.

The more popular method I saw was the "Dot" method. Then others say the ""Spread" method was best. Arguements went into how Heat is measureable and that somes methods will cause your CPU to be hotter by a good 5-10 degrees.

Dot Method
Apply a pea/ rice size dot on the middle of the CPU then place the heatsink on top. Let the paste naturally spread and it will cover the most important part.. the cores.

Spread Method
Apply a dot on the middle of the CPU then ue a credit card/ buisness card/ clean piece of metal to spread the paste of the entire surface of the CPU then rest the heatsink on top.

People were saying the "Spread" method produces to many air pockets/ bubbles and is harder to control the thickness of the paste.

I realise there is the line and cross method aswell, each with the own fanboys ready to flame another method and get all technical about it.

I plan to overclock (Well duh! I am getting the K edition) so I just need a CORRECT and SAFE method to aplly the paste so I don;t ruin my $300 CPU.

All help is apperciated. Thanks!

[Deleted]

Ever since I've been building computers I've been using the spread method. The rice/pea method never really appealed to me, I've tried it a few times but got exactly the same results as with spreading. Currently running an i5 2500k @ 5ghz with a Thermalright Venomous X RT with Arctic Silver.

So I guess you should use the method that you're the most comfortable with.

[Deleted]

They're all Safe, don't worry about that. Far more 'dangerous' to apply too much thermal Paste - and Apple and other OEMs are more than happy to do just that.

[Naphta]

In general spreading introduces air bubbles thus making heat transfer less effective. If you can do it flawlessly then it's probably better than the rice/pea method.

[Afrospinach]

I have always spread my paste and got some pretty good improvements over the factory stuff. I have read the pea or line method is the correct way to do it though. Whatever you do just keep an eye on your temps and you will be fine. I recently put a new heatsink on my i7 920(which are hotter than any sandy bridge afaik) and was getting some pretty high temps, nothing damaging. I checked the paste and found I had actually forgetten to remove thin plastic shield on the bottom of the heat sink. My point? You would probably have to try pretty hard to get paste THAT bad and it still performed acceptably(aside from the really noisy fan action).

[nbm02ss]

Here's a fun little fact about heat transfer; Heat will automatically transfer itself through the most appropriate medium. This means that if there's something with active particles available such as liquid, "goo", or air, it'll transfer to that. Otherwise, it's forced to transfer directly to solid.

It generally prefers the medium that's most free moving, which would be air. If air isn't available, or there's isn't enough of it, it'll simply overheat unless a liquid or paste type substance is in contact with it. Obviously though, material does have an effect, as Afrospinach proved above with the mention of not removing the plastic shield on a heatsink.

Essentially, both of them generally produce equal results if done correctly.

Personally, i used to spread. I thought that it'd be much better to do so. However, once i realised that the heat would simply transfer through a smaller area at the same efficiency, i started using the pea method. It's similar with watercooling. I used to use watercooling in a previous rig. I started with 8mm ID tubing. I thought that 1/2" tubing would prove to be more efficient. Unfortunately, what i didn't account for was the pressure you get in smaller diameter tubing, and sure enough, even with higher flow tubing and high flow components, i saw almost no difference in performance.

So, pea or spread, both produce roughly equal results simply due to the nature of energy (or to be specific, heat) transfer.

These Sandybridge chips are incredibly small. I mean damn, the actual dimension of them astounds me. You don't even want a pea sized amount on these. It needs to be a little less. Even just squeezing a small amount out and pressing it onto the center of the chip should be enough.

This X1000. I used a pea sized amount when I first hooked up the H70, and yup, way too much. Reduced it to the relative size of a BB and it's been spot on in temps ever since.

[Asera]

I usually dab a bit on my finger (with a piece of saran wrap over said finger), spread a really thin layer across the heat spreader and the bottom of the heatsink, then dab a BB size drop in the middle of the spreader and apply the hsf. Been doing that since the old spreader-less Athlon XP days.

You really don't need much at all, I got about 4 years use out of a tube of AS5 which I used at least once every month and a half on various coolers.

[Plasmon]

Here's a fun little fact about heat transfer; Heat will automatically transfer itself through the most appropriate medium. This means that if there's something with active particles available such as liquid, "goo", or air, it'll transfer to that. Otherwise, it's forced to transfer directly to solid.

It generally prefers the medium that's most free moving, which would be air. If air isn't available, or there's isn't enough of it, it'll simply overheat unless a liquid or paste type substance is in contact with it. Obviously though, material does have an effect, as Afrospinach proved above with the mention of not removing the plastic shield on a heatsink.

Essentially, both of them generally produce equal results if done correctly.

Personally, i used to spread. I thought that it'd be much better to do so. However, once i realised that the heat would simply transfer through a smaller area at the same efficiency, i started using the pea method. It's similar with watercooling. I used to use watercooling in a previous rig. I started with 8mm ID tubing. I thought that 1/2" tubing would prove to be more efficient. Unfortunately, what i didn't account for was the pressure you get in smaller diameter tubing, and sure enough, even with higher flow tubing and high flow components, i saw almost no difference in performance.

So, pea or spread, both produce roughly equal results simply due to the nature of energy (or to be specific, heat) transfer.

...

I feel uneasy about correcting a mod... especially a nice one, but what you've said about heat transfer isn't correct at all. I know this because I'm a materials engineer.

First of all there are 3 types of heat transfer, convection, conduction, and radiation. The transfer of heat from the chip to the heat sink is purely conduction, while the transfer from the heat sink outward is dominated by convection. What you have described about the heat transfer from the chip, through the thermal paste, and to the heat sink is not an accurate representation of the mechanisms of heat conduction.

Here's what happens. When two surfaces are pressed together, no matter how flat they appear to our eyes, they aren't anywhere near atomically flat, and likely have a roughness somewhere near 1 micron. Diamond paste that is often used to smooth materials to a mirror-like finish often has a grain size of 1 micron, so it can't polish to a degree finer than it's own grain size. This roughness in the surfaces of the two materials (the heat sink and the chip casing surface) means that the actual direct contact surface area is significantly smaller than the macro-scale area of the surface. This means there are many voids or air pocket. The problem is that an air gap is nowhere near as conductive as two surfaces in direct contact at the nano-scale. In heat transfer calculations we often model them like an electric circuit, using resistors to represent the resistance to heat transfer. At any surface we add a resistor to represent the "contact resistance" between the two materials, which takes into consideration the poor heat transfer ability due to the presence of the tiny air gaps.

Heat transfer by conduction strongly depends on the surface area, (it's directly proportional to surface area), so the presence of these low conductivity air gaps is detrimental to the heat transfer efficiency. The role of the thermal paste is only to fill the microscopic voids with a somewhat conductive material and the result is the reduction of thermal contact resistance. The paste material must be very good at wetting the two solid materials to ensure there are a minimal amount of gaps and so it has a low surface energy, low viscosity when under pressure or elevated temperature, and the higher thermal conductivity the better.

The ideal application of thermal paste keeps it as thin as possible while minimizing the amount of air gaps. You want to keep it thin because the conductivity is nowhere near as good as that of the two solid materials surrounding it, so it still causes thermal resistance itself. The spreading technique of choice depends on the viscoelastic properties of the thermal paste. If it is the type that spreads into a very thin layer upon the application of pressure and elevated temperature then the dot method would be superior. If it's not good at spreading on it's own, then manual spreading would be more beneficial. They spreading techniques are not equivalent and the method of choice has nothing to do with the nature of heat transfer.

What you've said about heat preferring to transfer through air isn't right at all. For example copper is approximately 16000 times better at heat conduction than air. (Yes that number is accurate.) Heat transfer by conduction occurs through phonons, which are quantum waves of atomic vibrations. The conductivity is therefore a function of the lattice structure at the atomic scale, and it is much more efficient in most solids compared to most liquids or gasses. Monocrystalline diamond is one of the materials with the highest thermal conductivity due to it's sp3 hybridized lattice structure. If diamond was super cheap and easy to shape it would be heavily used instead of copper or aluminum. Many people confuse thermal and electrical conductivity, but they are not the same mechanism. Metals are highly thermally conductive because the free electrons transfer heat as well as electricity but this correlation in conductivity between electricity and heat doesn't occur in most other materials. Diamond is terrible at conducting electricity without the presence of substitutional dopant atoms. The solids that are poor at heat transfer have microstructures or crystal structures that hinder the transfer of phonons. Plastics are generally bad because they have a low density and a mostly amorphous structure as well as poor inter-chain transfer mechanics. Glass is poor because it is amorphous. Some ceramic materials are good (single crystals of sapphire and diamond for example) and some are bad, but this strongly depends on the microstructure of the specific piece of material as well as the crystal structure. There are many ways that the structure can scatter phonons and render the energy transfer much less useful.

As a general rule for thermal conductivity you can assume this: solid>liquid>>gas. There are exceptions though.

Your experience with water cooling and tube size has nothing to do with heat transfer, it's about fluid mechanics. No matter what the diameter of your tube, the surface area between the waterblock and the chip casing is exactly the same, and the surface area between the water and the internal surface of the waterblock is also the same. Thicker tubing won't change much if your pump is using the same amount of power unless the tubing was so thin that it was causing an excessive pressure drop. Generally when you increase the diameter of a tube/pipe, the speed of the liquid decreases proportionally, so you have the same amount of liquid moving through the tube in both cases. Thin tube means faster moving liquid with a small profile, while a thick tube means slower moving liquid with a larger profile, and both have equal volume transferred per area per second.


/end science rant.

[llDemonll]

I feel uneasy about correcting a mod...

We're all people, I've been corrected numerous times on here and I much prefer it to spewing wrong information.

I don't know how small the SB chips are but I did a 'U' or an 'N' or something on my 1366...4 cores, little bit for each and haven't had a problem

[ispano]

I feel uneasy about correcting a mod... especially a nice one, but what you've said about heat transfer isn't correct at all. I know this because I'm a materials engineer.

First of all there are 3 types of heat transfer, convection, conduction, and radiation. The transfer of heat from the chip to the heat sink is purely conduction, while the transfer from the heat sink outward is dominated by convection. What you have described about the heat transfer from the chip, through the thermal paste, and to the heat sink is not an accurate representation of the mechanisms of heat conduction.

Here's what happens. When two surfaces are pressed together, no matter how flat they appear to our eyes, they aren't anywhere near atomically flat, and likely have a roughness somewhere near 1 micron. Diamond paste that is often used to smooth materials to a mirror-like finish often has a grain size of 1 micron, so it can't polish to a degree finer than it's own grain size. This roughness in the surfaces of the two materials (the heat sink and the chip casing surface) means that the actual direct contact surface area is significantly smaller than the macro-scale area of the surface. This means there are many voids or air pocket. The problem is that an air gap is nowhere near as conductive as two surfaces in direct contact at the nano-scale. In heat transfer calculations we often model them like an electric circuit, using resistors to represent the resistance to heat transfer. At any surface we add a resistor to represent the "contact resistance" between the two materials, which takes into consideration the poor heat transfer ability due to the presence of the tiny air gaps.

Heat transfer by conduction strongly depends on the surface area, (it's directly proportional to surface area), so the presence of these low conductivity air gaps is detrimental to the heat transfer efficiency. The role of the thermal paste is only to fill the microscopic voids with a somewhat conductive material and the result is the reduction of thermal contact resistance. The paste material must be very good at wetting the two solid materials to ensure there are a minimal amount of gaps and so it has a low surface energy, low viscosity when under pressure or elevated temperature, and the higher thermal conductivity the better.

The ideal application of thermal paste keeps it as thin as possible while minimizing the amount of air gaps. You want to keep it thin because the conductivity is nowhere near as good as that of the two solid materials surrounding it, so it still causes thermal resistance itself. The spreading technique of choice depends on the viscoelastic properties of the thermal paste. If it is the type that spreads into a very thin layer upon the application of pressure and elevated temperature then the dot method would be superior. If it's not good at spreading on it's own, then manual spreading would be more beneficial. They spreading techniques are not equivalent and the method of choice has nothing to do with the nature of heat transfer.

What you've said about heat preferring to transfer through air isn't right at all. For example copper is approximately 16000 times better at heat conduction than air. (Yes that number is accurate.) Heat transfer by conduction occurs through phonons, which are quantum waves of atomic vibrations. The conductivity is therefore a function of the lattice structure at the atomic scale, and it is much more efficient in most solids compared to most liquids or gasses. Monocrystalline diamond is one of the materials with the highest thermal conductivity due to it's sp3 hybridized lattice structure. If diamond was super cheap and easy to shape it would be heavily used instead of copper or aluminum. Many people confuse thermal and electrical conductivity, but they are not the same mechanism. Metals are highly thermally conductive because the free electrons transfer heat as well as electricity but this correlation in conductivity between electricity and heat doesn't occur in most other materials. Diamond is terrible at conducting electricity without the presence of substitutional dopant atoms. The solids that are poor at heat transfer have microstructures or crystal structures that hinder the transfer of phonons. Plastics are generally bad because they have a low density and a mostly amorphous structure as well as poor inter-chain transfer mechanics. Glass is poor because it is amorphous. Some ceramic materials are good (single crystals of sapphire and diamond for example) and some are bad, but this strongly depends on the microstructure of the specific piece of material as well as the crystal structure. There are many ways that the structure can scatter phonons and render the energy transfer much less useful.

As a general rule for thermal conductivity you can assume this: solid>liquid>>gas. There are exceptions though.

Your experience with water cooling and tube size has nothing to do with heat transfer, it's about fluid mechanics. No matter what the diameter of your tube, the surface area between the waterblock and the chip casing is exactly the same, and the surface area between the water and the internal surface of the waterblock is also the same. Thicker tubing won't change much if your pump is using the same amount of power unless the tubing was so thin that it was causing an excessive pressure drop. Generally when you increase the diameter of a tube/pipe, the speed of the liquid decreases proportionally, so you have the same amount of liquid moving through the tube in both cases. Thin tube means faster moving liquid with a small profile, while a thick tube means slower moving liquid with a larger profile, and both have equal volume transferred per area per second.


/end science rant.

You shouldn't feel uneasy at all. You know the subject due to the fact you work in the field, you have a lot of first hand experience with it. You know your stuff when it comes to this subject. Correcting someone when you have that level of knowledge, should be normal. And if they take offense, it's their problem, not yours. You're only providing them with the correct information.

Not saying he'll take it that way, just if you have that much knowledge to back you up, don't feel wrong to correct someone. Better that they have the correct info, instead of spreading incorrect info.

[Cilraaz]

We're all people, I've been corrected numerous times on here and I much prefer it to spewing wrong information.

Pretty much what Demon said here. I don't want to speak for other mods, but a proper correction (ie. not "OMG! UR SO RONG AND DUM!") is usually welcome. I enjoy learning things I didn't know before... even if it means that something I've spouted is wrong.

On-Topic: For the 2nd-gen Core i CPUs, Arctic Silver suggests the line method. I used that with my 2500k and have had zero heat issues. I'm running 4.6GHz @ 1.35v, 47°C during WoW, with an ambient temp of 22°C. I do suggest against the spread method, though, as it has a higher tendency of creating air pockets.

Arctic Silver's website has a list of suggested methods dependent on CPU type, which can be found here.

[wildemu]

i just go to the arctic silver site and look at their manual for any processor I am working on.

Usually, it's dot on the processor, spread on the heatsink.

[Deleted]

I use artic silver paste, i spread a thin layer onto CPU, put heaksink on, done.

[Plasmon]

I guess I was being overly cautious. Before I started writing that I thought the post might come off as a bit more offensive than what it turned out to be... but incorrect science makes my spidey senses tingle so I had to fix it.

[Asera]

Pretty much what Demon said here. I don't want to speak for other mods, but a proper correction (ie. not "OMG! UR SO RONG AND DUM!") is usually welcome. I enjoy learning things I didn't know before... even if it means that something I've spouted is wrong.

On-Topic: For the 2nd-gen Core i CPUs, Arctic Silver suggests the line method. I used that with my 2500k and have had zero heat issues. I'm running 4.6GHz @ 1.35v, 47°C during WoW, with an ambient temp of 22°C. I do suggest against the spread method, though, as it has a higher tendency of creating air pockets.

Arctic Silver's website has a list of suggested methods dependent on CPU type, which can be found here.

Welp, I think I did application on my i5 wrong. That coupled with using the drags of my AS5 probably explains why my temperatures aren't as good as I like.

[Azerox]

I spread it on the CPU and put the cooler on top of it.

Same for GPU, spread all he way so the cooling has the best contact, i dont think a dot will achieve that

Using Artic Silver 5 for everything, but u need to watch out with spread with Artic Silver that u keep it on the survace of the cpu/gpu.

It is also electrical conductive as it is metal ... if your new to this it is best to use Ceramic-based, expecialy on the GPU

http://www.techpowerup.com/printarticle.php?id=134