Thermal Paste Comparison, Part Two: 39 Products Get Tested

[4Ryan6]

All thermal compound is supposed to do, is fill the microscopic imperfections between the 2 contacting surfaces filling the microscopic air voids and that's it.

Replace the air with a good thermal conductor, to transmit the heat from one surface to the other, no thick layer!

A thick layer is bad!

The least used you can get away with the better the cooling performance, I don't care what brand it is.

What I've always done for years and works fine for me is once I've seated the HSF on the CPU and clamped it, I then unclamp and gently lift the HSF off.

This gives me a nice thin coating on both surfaces. The paste on the HSF is then cleaned off and I replace the HSF on the CPU with just the layer left on the CPU.

Basically this reduces the amount of paste by around 50% (give or take) but means I have a pretty thin even layer across both surfaces filling in those tiny tiny gaps.

Works a treat.

Did you test before and after temperature results?

 

[Maxx_Power]

And I thought Arctic silver 5 was the best after seeing all those reviews on newegg!

Those are user reviews, by no means are they rigorous (a very few people will actually buy several pastes and compare them on the same setup, then write a review).

AS5 did have the advantage of coming to market very early on, nearly a decade ago, I think. Back then, there were very few competitors, and the few that were popular like Zalman (poor pastes, but popular heatsinks) didn't try as hard to formulate something original.

PS. I thought I'd point out that the results here at Toms very much echo the results of Skinnee Labs (websites down for the moment), a site whose testing methodology is by far the most rigorous, in my opinion.

 

[hhh1964]

Impressive and real quality work!
This will be a reference for some years.

 

[drwho1]

very good and unbiased article.

 

[maestintaolius]

You guys really should have tested the OEM standards as well, a big one would be Shin-Etsu X23-7783D, odds are if you buy a decent heat sink, that's likely what's on it. You should have tested some phase change materials as well. Unfortunately, you really need to buy the sealed can and not the stuff in syringes as X23 uses a volatile solvent to reduce application viscosity and when you buy it as a syringe, that solvent will be gone and the viscosity won't be the same. Anyway, most of the consumer grade TIMs are based on marketing gimmicks rather than actual thermal performance (e.g. silver filled compounds and their bulk thermal conductivity values).

In the case of thermal greases, thermal conductivity of the filler particles isn't as important as bond line thickness. This is why your liquid metal solutions did so well, the bond line thickness in those cases are typically limited by tolerances and material viscosity. This is also why things like silver filled compounds don't do as well as people think they should based on bulk thermal conductivity values as bulk thermal conductivity isn't as important in thin bond line applications as interfacial thermal resistance and particle size are. Silver compounds tend to be rather large and flaky so they don't lend themselves well to low viscosities, ease of processing, or thin bond lines.

I've seen other suggestions here too about using diamond. We've played with those but diamond has lots of issues with it, namely phonon scattering and processing difficulty. Alumina is already harsh enough of mixing vessels and pumping/dispensing systems, diamond would be even worse, so I doubt there will ever be any serious industry production. There will likely be some small 'garage' companies that make diamond filled TIMs but phonon scattering seems to be a major factor in decreasing the thermal performance and making it such that it doesn't perform any better than AlN, ATH or alumina, despite diamonds obscenely high thermal conductivity.

Similarly, graphite, despite having a very high TC, doesn't work as well as you'd think either. Graphite has a very high thermal conductivity, in the x-y plane, but the z plane is extremely low. To combat this, the particles are made into conglomerates with random z-axis orientation which results in the overall thermal conductivity not being much greater than that of standard fillers, also conglomerates like to break up in mixing, adding more complications. Graphite does have fairly small particle size though, making for great bond line thickness, however that also means the surface area to volume ratio is very high, resulting in a very high viscosity relative to filler loading which serves to fight against going to a small bond line at low pressures.

I would also like to caution people regarding liquid metal. DO NOT USE LIQUID METAL ON ALUMINUM. The liquid metals used in TIMs will dissolve aluminum over time (aluminum is soluble in the liquid metal), you can only use liquid metal TIMs on copper heat sinks, the heat spreaders on CPUs are typically copper coated with nickel and that is okay too. The other issue with liquid metals is they like to separate from the silicone carrier so you can end up with 'gobs' of liquid metal separating out from the TIM over time.

 

[maestintaolius]

double post, sorry

 

[maestintaolius]

All the hype aside, could Tom's include an actual industrial "Silicone Heat Transfer Compound", such as the one by MG Chemicals :http://www.mgchemicals.com/products/greases-and-lubricants/thermal-greases/silicone-heat-transfer-compound-860/, any of the future comparisons. If this stuff is good to use in mass industrial applications, how can it not be any better then let's say AS5.

Plus, AS5 can short out your mobo if some of it gets on the PCB and it costs 10 times as much as the industrial stuff and I don't think it is 10 times better.

A few things:

1) Have you looked at the technical specifications of that particular paste ? It says, the thermal conductivity is only 0.773-0.657 W/mK, which is about a order of magnitude LESS than tested products (AS5 at 9 W/mK and MX4 at 8.5 W/mK).

2) The compound is only made from zinc oxide and a binder oil. This is no different from the cheap Zalman compounds (the generic white paste).

3) These pastes are meant for low power density applications, I have 2 tubs, and they are piss poor on computers (high power density applications), but just fine for what they are made for - cooling very low powered circuits like voltage regulators (not for computer use, but analog use), opamps, low powered transistors (like for amplifiers). This is the stuff you find inside your stereo, between the transistors/chip amps and the heatsink, where the chip is dissipating about 50 watts of heat maximally (and not prolonged) over a surface area 10 times larger than a CPU-heatsink contact.

4) The AS5 isn't conductive. It doesn't contain un-oxidized silver. It is slightly capacitive, more so than other compounds. But it isn't going to burn out a computer by shorting it, it is not a conductor. That said, I much prefer Ceramique 2 (the original Ceramique was terrible) or MX-4.

In the case of grease application TIMs, bulk thermal conductivity is a meaningless number, it's mostly just marketing, I could run down to the lab and make you a grease that was 20 W/m-K in about 20 minutes but it'd completely fail you as a thermal grease. For greases, the more important number/chart is the thermal resistance vs pressure. The best greases available will actually have fairly low bulk thermal conductivity as the goal is to have a low viscosity with a small filler size, allowing the compound to go to thin bond line. The best way to accomplish that is to have low filler levels with very small particles, as small particles have high surface area:volume ratios you can't load them too heavily or the viscosity shoots through the roof and it takes too much pressure to reach bond line.

That said, ZnO fillers are poor, typical high performance greases will use ATH, ALN, BN, alumina, aluminum or liquid metals. The ZnO filled greases are usually just lubricating greases that the company also happens to dual purpose sell as a thermal grease.

 

[alextheblue]

Excellent article. Looking forward to seeing more compounds added, especially ones in the easy-to-use category. I'm getting too old to fight with the really high-viscosity thermal pastes, carefully spreading it, heating it, cursing at it, etc. No thank you. This article reinforces my decision to get MX-4 again next time around. Easy to use, good all-around performer, relatively cheap. Hard to screw it up too - battling with an awkward cooler in an awkward mATX case doesn't seem to matter much.

Heck, if there was a thermal pad that came close enough, I might settle for that for some builds.

 

[jimmysmitty]

I'd be really interested to know how well the paste included with Corsairs H100i cooler performs in comparison to these. I went ahead and used it since it was already applied to the cooler. Everything seems to work well, but my system is so well cooled that the temps inside the case only run a couple degrees above ambient. I was actually able to set my heatsink fans to their lowest speed (500rpm, almost silent) and get barely a 1 degree F rise in temp. on a 3750K at stock speeds. I've never bothered OCing, since my computer rarely works hard enough to get to max speed on anything I do.

Per Corsair, they say what they have works best compared to anything else they have tested and wont change it.

Its hard to say for sure.

Ryan, thanks for the input. I liked IC Diamond but due to the insane amount of pressure I moved on to Zalmans current stuff as it works way better than their older STG1 and so far has kept my CPU happy. I also have a 9900Max and Zalman is well known for their mirror like finish so I doubt anything else would make a massive difference since the heatsink is already polished beyond what the majority of companies do.

Yeah, I have no complaints about the current Corsair compound, whatever it may be. I'm curious about the amount/thickness they provide with the package, since it's already applied to the heatsink. Maybe it should be less for Intel processors since they're smaller than AMD... I dunno. I haven't attempted to remove it since installation since I haven't had a need. But, after reading this article, it sets my inquiring mind off onto plenty of directions.

I would assume what they put on is sufficient for both since they do tons of internal testing. There is no way they can do one cooler for Intel only, the other for AMD etc.

I wouldn't mess with it if it keeps your temps where they need to be.

Now I just need Corsair to release a H110i as I want to throw it up top in my 500R but want the better air pressure fans they have.

And I thought Arctic silver 5 was the best after seeing all those reviews on newegg!

AS5 was the best. A long time ago. Things change and whats the best now may change later down the road.

Disappointed in Arctic Silver 5 after having been told time and again, not that long ago, it's the best stuff out there. Also needs a long burn-in time from what I recall.

It can take up to a year to cure. Which is pretty long TBH.

 

[wdmfiber]

I'd be really interested to know how well the paste included with Corsairs H100i cooler performs in comparison to these. I went ahead and used it since it was already applied to the cooler. Everything seems to work well, but my system is so well cooled that the temps inside the case only run a couple degrees above ambient. I was actually able to set my heatsink fans to their lowest speed (500rpm, almost silent) and get barely a 1 degree F rise in temp. on a 3750K at stock speeds. I've never bothered OCing, since my computer rarely works hard enough to get to max speed on anything I do.

Most ppl that wiped the factory applied paste off their H80/H100 and applied something else... regretted it.

If you get a new CPU, reapply a quality Cooler Master paste.

 

[Dextron]

YOU NEARLY GAVE ME A HEART ATTACK!!! - "there may even be those who are more courageous than I and use it on graphics cards" - I used this (Coollaboratory's Liquid Ultra) on my brand new GTX Titan!
Truth be told, it's working wonders along with my custom-built liquid cooling loop, but had this article existed when I was planning my build, I would have steered clear of the stuff... and so we return to my opening statement: to fear what could have happened, but luckily didn't...

 

[4Ryan6]

YOU NEARLY GAVE ME A HEART ATTACK!!! - "there may even be those who are more courageous than I and use it on graphics cards" - I used this (Coollaboratory's Liquid Ultra) on my brand new GTX Titan!
Truth be told, it's working wonders along with my custom-built liquid cooling loop, but had this article existed when I was planning my build, I would have steered clear of the stuff... and so we return to my opening statement: to fear what could have happened, but luckily didn't...

Did your Titan have a heat spreader over the GPU die
if you used Liquid Ultra I hope for your sake it did!

Liquid metals performance degrades over time as it dries out from the heat if you use it long enough you'll find that out, and is hard to remove because it seems to etch itself into the contacting surfaces.

Using the liquid metals is almost a guaranteed warranty loss, because defacing the writing on either a CPU or GPU heat spreader removing the liguid metal, is a warranty loss situation, there's a warning on either the Coolaboratory package or the instruction sheet in the package, regarding that possibility.

Coolaboratory wants to make sure you understand that, the warning is there to absolve them from any responsibility, because they know full well what's going to happen!

Quote from instructions below:

Please find more information and a detailed manual on www.coollaboratory.com.

Please notice that

The warranty of CPUs or coolers generally expires when another heat conduction medium than the manufacture of the components recommended is used.

 

[Dextron]

Did your Titan have a heat spreader over the GPU die
if you used Liquid Ultra I hope for your sake it did!

Liquid metals performance degrades over time as it dries out from the heat if you use it long enough you'll find that out, and is hard to remove because it seems to etch itself into the contacting surfaces.

Using the liquid metals is almost a guaranteed warranty loss, because defacing the writing on either a CPU or GPU heat spreader removing the liguid metal, is a warranty loss situation, there's a warning on either the Coolaboratory package or the instruction sheet in the package, regarding that possibility.

Coolaboratory wants to make sure you understand that, the warning is there to absolve them from any responsibility, because they know full well what's going to happen!
[/quotemsg]

No...it does not have a heat spreader. I faithfully believe that isopropyl alcohol can dissolve the stuff and if not, plan B:

Coollaboratory's Liquid Ultra is an alloy of several metals, it's liquid because Gallium (one of the metals in the alloy) has a very low melting point (I know it's gallium because of the "do not use with aluminium" warning; liquid gallium can alloy with solid aluminium, turning the aluminium into wet cardboard); gallium when exposed to heat and air for prolonged times, tends to form gallium oxide (white crystalline solid, not a good thermal conductor and not liquid), that's probably where the "wet" part of the compound is going (believing in the conservation of matter)...plan B is to try and dissolve the gallium oxide with a weak acid solution in which it is soluble (unlike the water and isopropyl alcohol in the provided cleaner) and then try to remove the remaining material with isopropyl alcohol; plan C is to remove the oxide and then add metallic gallium to what remains; plan D is to curl up and cry because I'm out of ideas; plan E is to think of something else; plan F is to do some research and then try to think of something else.

 

[Calculatron]

The missing thermal compounds some of you are asking about were more than likely not submitted to be tested.

The companies submitting their products to be tested are also giving their permission to do so.

It's not like Toms went out and bought every compound out there to be tested and left some on the shelves so to speak.

Ah, I should have figured that this review would be the same as the others. Alas! That explains why my offer to send in my tube of Dow Corning TC-5022 went unanswered.

 

[anubus45]

Nice article, though I would've liked to see mention of Indigo Xtreme though. I know it's not a "paste" per-se, but I think it does deserve mention in this type of article, because it tops performance on every single chart I've seen it on, and it is rather unique.

 

[4Ryan6]

Nice article, though I would've liked to see mention of Indigo Xtreme though. I know it's not a "paste" per-se, but I think it does deserve mention in this type of article, because it tops performance on every single chart I've seen it on, and it is rather unique.

Indigo Extreme requires a 90c reflow temperature maintained long enough to melt the compound to it's flow point to seat properly.

Most of us never have any intentions of allowing our CPUs to reach those 90c temperatures, why would we purposely force it to do so.

I was interested in Indigo Extreme until I discovered that, in the link click, reflow procedure for Indigo Extreme.

My CPU temperature never gets anywhere near 90c!

http://indigo-xtreme.com/

 

[FormatC]

You guys didn't test IC Diamond?

I've tested it after this translation. But you can found the results of IC Diamond 24 in our charts and in a short review from me (in German, but understandable):

http://www.tomshardware.de/Innovation-Cooling-Diamond-24-Review,testberichte-241361.html

There is also a short How-To about the best usage of this thick paste.

 

[InvalidError]

Indigo Extreme requires a 90c reflow temperature maintained long enough to melt the compound to it's flow point to seat properly.

Most of us never have any intentions of allowing our CPUs to reach those 90c temperatures, why would we purposely force it to do so.

More importantly: if the compound does require 90C to reflow properly, that would be 90C TCase when most CPUs have TCasemax in the 67-75C range.

 

[Maxx_Power]

All the hype aside, could Tom's include an actual industrial "Silicone Heat Transfer Compound", such as the one by MG Chemicals :http://www.mgchemicals.com/products/greases-and-lubricants/thermal-greases/silicone-heat-transfer-compound-860/, any of the future comparisons. If this stuff is good to use in mass industrial applications, how can it not be any better then let's say AS5.

Plus, AS5 can short out your mobo if some of it gets on the PCB and it costs 10 times as much as the industrial stuff and I don't think it is 10 times better.

A few things:

1) Have you looked at the technical specifications of that particular paste ? It says, the thermal conductivity is only 0.773-0.657 W/mK, which is about a order of magnitude LESS than tested products (AS5 at 9 W/mK and MX4 at 8.5 W/mK).

2) The compound is only made from zinc oxide and a binder oil. This is no different from the cheap Zalman compounds (the generic white paste).

3) These pastes are meant for low power density applications, I have 2 tubs, and they are piss poor on computers (high power density applications), but just fine for what they are made for - cooling very low powered circuits like voltage regulators (not for computer use, but analog use), opamps, low powered transistors (like for amplifiers). This is the stuff you find inside your stereo, between the transistors/chip amps and the heatsink, where the chip is dissipating about 50 watts of heat maximally (and not prolonged) over a surface area 10 times larger than a CPU-heatsink contact.

4) The AS5 isn't conductive. It doesn't contain un-oxidized silver. It is slightly capacitive, more so than other compounds. But it isn't going to burn out a computer by shorting it, it is not a conductor. That said, I much prefer Ceramique 2 (the original Ceramique was terrible) or MX-4.

In the case of grease application TIMs, bulk thermal conductivity is a meaningless number, it's mostly just marketing, I could run down to the lab and make you a grease that was 20 W/m-K in about 20 minutes but it'd completely fail you as a thermal grease. For greases, the more important number/chart is the thermal resistance vs pressure. The best greases available will actually have fairly low bulk thermal conductivity as the goal is to have a low viscosity with a small filler size, allowing the compound to go to thin bond line. The best way to accomplish that is to have low filler levels with very small particles, as small particles have high surface area:volume ratios you can't load them too heavily or the viscosity shoots through the roof and it takes too much pressure to reach bond line.

That said, ZnO fillers are poor, typical high performance greases will use ATH, ALN, BN, alumina, aluminum or liquid metals. The ZnO filled greases are usually just lubricating greases that the company also happens to dual purpose sell as a thermal grease.

I didn't see any data on their website about the thermal resistance or conductivity vs. pressure. It seems like you may be suggesting that these thermal greases are non-Newtonian fluids ? If the viscosity sharply changes as a function of load, I mean. My understanding was that these were very much Newtonian fluids with a well defined viscosity, because of the non-polymerized state of the internals.

 

[InvalidError]

It seems like you may be suggesting that these thermal greases are non-Newtonian fluids ?

If you compress thermal grease/paste to the point where its solid contents that were in colloidal suspension in the grease/oil/whatever prior to application start packing into a solid mass, it isn't a fluid anymore.

 

[Maxx_Power]

It seems like you may be suggesting that these thermal greases are non-Newtonian fluids ?

If you compress thermal grease/paste to the point where its solid contents that were in colloidal suspension in the grease/oil/whatever prior to application start packing into a solid mass, it isn't a fluid anymore.

I see your point. So there is a preferential seeping or separation (of the suspension) of the mixture under a regular application process ? I am guessing this is not the same as a phase transition under pressure, which requires a lot higher pressures.

 

[g-unit1111]

Would love to IC Diamond as well. However I would like to suggest some 'For Fun Only' pastes that you should give it a whirl.

- Mayonnaise
- Shaving Cream
- Cream Cheese

I'd also like to see:

- Nail polish
- Plaster compound
- Caulking compound
- Rubber cement
- Hobby glue
- Face mask cream

We could have some fun with this! :lol:

 

[InvalidError]

I see your point. So there is a preferential seeping or separation (of the suspension) of the mixture under a regular application process ?

It is a little like packing sand: you have sand particles of different shapes and sizes. By applying vibration and pressure, you can force smaller particles to squeeze in voids between larger particles to fill gaps. Eventually, you end up with densely packed sand that feels practically solid. For dams and artificial islands, water is often used as the "lubrication" to help sand particles move around until they become packed densely enough to become nearly water-tight.

Almost the same process occurs with metal oxide powder pastes over time: you put the paste in, pressure and vibrations slowly cause particles to pack tighter together, excess oil/grease seeps out and eventually you have a practically solid, hopefully uniform and gap-less mass if the grease had the right mix of particle sizes to make it happen.

 

[Maxx_Power]

I see your point. So there is a preferential seeping or separation (of the suspension) of the mixture under a regular application process ?

It is a little like packing sand: you have sand particles of different shapes and sizes. By applying vibration and pressure, you can force smaller particles to squeeze in voids between larger particles to fill gaps. Eventually, you end up with densely packed sand that feels practically solid. For dams and artificial islands, water is often used as the "lubrication" to help sand particles move around until they become packed densely enough to become nearly water-tight.

Almost the same process occurs with metal oxide powder pastes over time: you put the paste in, pressure and vibrations slowly cause particles to pack tighter together, excess oil/grease seeps out and eventually you have a practically solid, hopefully uniform and gap-less mass if the grease had the right mix of particle sizes to make it happen.

Ahh okay, it is a structural, pore-space related packing process. I just wasn't aware that the pastes were under sufficient pressure to actually undergo this process, I assumed that the pastes became harder over time purely due to evaporation, leaving the filler materials behind.

 

[InvalidError]

Ahh okay, it is a structural, pore-space related packing process. I just wasn't aware that the pastes were under sufficient pressure to actually undergo this process, I assumed that the pastes became harder over time purely due to evaporation, leaving the filler materials behind.

No need for pressure. The packing and separation process can occur even inside a tube resting on a table. It will simply take a few years instead of a few weeks or months - colloidal suspension does not last forever.

As for evaporation, silicon is the base of many greases and does not evaporate. When you pull a HSF off a CPU that got pasted with a silicon-based thermal grease after a few months, you will usually see a ring of "wet" transparent stuff around the clay-like paste patch. That's the silicon oil that got pressed out of the thermal interface over time.

The process will happen regardless of pressure but more pressure does make it happen faster.