Thermal Paste Comparison, Part One: Applying Grease And More

Choosing The Right Paste: More Than A Matter Of Price

Because thermal paste is a high-margin product, the market is crowded. While the exact composition of most products is a well-kept secret, a Google search makes it pretty easy to get a list of typical ingredients. The upper temperature limit is typically 150 °C, though some pastes claim to withstand up to 300 °C or more.

The composition of a paste determines its thermal conductivity, its electrical conductivity, its viscosity, and its durability. But what is a paste really made of? Basic compounds consist of zinc oxide and silicone as a binding agent. However, such simple combinations are barely sold anymore. Most vendors start with these ingredients and add other materials, like aluminum. Case in point, the Prolimatech PK1 sports 60-85% aluminum content, 15-25% zinc oxide, and 12-20% silicone oil, as well as an anti-oxidation agent. Some ingredient lists are more mysterious. For instance, the one printed on be quiet!'s DC 1 syringe ambiguously specifies 60% metal oxide, 30% zinc oxide (wait a second; since when is zinc not a metal?), and 10% silicone.

Some pastes, like Arctic Silver 5, even contain silver. Other pastes are based on graphite, like the professional-grade WLPG 10 by Fischer Elektronik, forego the silicone, and claim very high thermal conductivity (10.5 W / m·K), but they are more difficult to apply and are typically electrically conductive. There are also pastes that employ carbon nanoparticles, though they're not suitable for most enthusiasts due to their electrical conductivity and price. The number of copper-based pastes on the market has shrunk, but if you search, you can still find a few.

I leave the more exotic thermal coupling solutions like liquid metal and metal pads for the second part of our tutorial. Applying these electrically conductive products is not without risk, and I don’t want to confuse anyone with a detailed discussion of them at this point. Let’s just say that they're for expert use only, and you'll want to satisfy a few prerequisites prior to applying them.

All pastes share one thing in common: regardless of their composition or price, they all fall short of heat sinks and spreaders with regard to thermal conductivity. Thus, a thermal paste is always the weakest link in the cooling chain, regardless of its price!

Create a new thread in the US Reviews comments forum about this subject
This thread is closed for comments
136 comments
    Your comment
    Top Comments
  • Nice article and bookmarked for reference. Looking forward for the next part.
    39
  • please tell me yo are also going to do the solder the heatsink to the cpu method? i forget what its called, but that is what i want to use for my next computer and would love to see how it stacks up.
    10
  • Other Comments
  • Nice article and bookmarked for reference. Looking forward for the next part.
    39
  • please tell me yo are also going to do the solder the heatsink to the cpu method? i forget what its called, but that is what i want to use for my next computer and would love to see how it stacks up.
    10
  • In the second section about advanced cooling methods, are you planning on discussing delidding CPUs and replacing thermal paste? If you do it might be worth mentioning that the delidding won't improve temperatures because of improved thermal paste conductivity but because of reducing the thickness of the paste. See http://forums.anandtech.com/showpost.php?p=34053183&postcount=566
    7
  • a really nice and helpful article!
    3
  • Huh, I do turn my heatsinks sometimes for optimal alignment so the heat pipes are perpendicular to the die. Depends if I got the room in the case and what ram is being used. Also heatsink dependent
    2
  • One of the best articles I've read on Tom's in years and that's saying something. Looking forward to part 2.
    9
  • ooooooooooh such a tease

    can't wait for part 2 - this was a great read!
    6
  • Loving that DHT-based design overlay picture on the first page. I've been telling my friends for a while to just get coolers with plated covers because the pipes miss the hotspot on intel CPU's, but no I'm full of bs apparently. This video is awesome btw, shows how spreads happen http://www.youtube.com/watch?v=EyXLu1Ms-q4
    2
  • How many volts does this "7 volt" unregulated power supply put out?

    Just curious. I have some 8/9/12 volt regulators that would eliminate the guessing games for resistor fan adapters(voltage depends on the fans current draw).

    I have seen unregulated 6 volt power supplies range from 8-over 12 volts at low loads.

    For a rather low price you can use a regulator to get whatever voltage you want :)

    ohh yeah and...
    I can't wait for the next part of this to be release
    4
  • From what I have seen it depends on the materials. AS5 was great for a while but thee are better ones out than that now such as Noctuas or Zalmans.

    I also enjoyed using the IC Diamond thermal paste as it proved to cool very well but since it has a diamond based substance it can scuff the heat spreader.
    2
  • Also would like to see an Ivy/Haswell test system since they run pretty hot and imo, they need more study on how to best cool them due to the TIM inside them.
    6
  • I always spread the paste manually. Never had issues with overheating.
    2
  • I am using dirt cheap masscool fanner-420.

    My temps are quite good - really the choice of cooler is much much more important than the choice of paste.
    0
  • "don’t apply too much. Otherwise, the paste will ooze out on all sides. If your paste is electrically conductive, you can almost be assured of hardware damage."

    Tell this to OEM's ever seen a hp, dell, Lenovo, Asus, Acer cpu after you take off the heatsink with thermal paste on it? it's oozed all over he place...
    8
  • I experimented with different application methods when I built my 4770K-based system. Small dot, large dot, X, line. No real difference, but the small dot produced the best results by ~2C. I used MX-4, which is so easy to apply that you can't really mess up.

    When delidding and applying Liquid Pro between the IHS and die, I "painted" a very thin layer. It was very difficult until the surface tension broke, then it was easy from there.
    1
  • Nice article, you guys ripped me a new one with the spread all over cpu method. Been doing that for a long time hah. Based off what you guys said i feel like it need to reapply paste considering the hot spot on my ivy bridge processor. I feel as if that method works although its very tedious and takes a long time to apply a even surface, i used Arctic MX-2 and it seemed to apply easy with some resistance to spreading evenly flat.. 30 minutes later walaa.. haha painted flat all over.. But i like that pea method in the middle seems to cover the hot spot quite well. Will have to try that out. Can't wait for the next part.
    0
  • Dude! this is great. This the first time since the Coppermine era that we started using thermal pastes widely that somebody put all the information together. Congrats guys great job. Well done.
    2
  • 2.66Ghz Q0 Q6600? What planet did I stumble upon? Hopefully one that still has Indigo Xtreme.
    1
  • Hey Tom's, I realize that you guys have limited time for these articles, and have to limit the scope. But I think it should be pointed out that not every one reading these articles are complete novices. In fact, I would wager those of us wanting to see the subtle differences between paste and cooler combinations are intermediate to advanced users. As such, in the future I think the risks involved should be left up to the reader. Having the comparison data to go with the risk would be helpful. Gaining .5C better temps for me would not be worth it. But if it dropped 2C on a GPU for my laptop... now that is tempting. As it stands, this data will not be available for those of us that would be interested.

    Otherwise, great article, can't wait to see the results.
    -9
  • Nice Job Igor, You have your ambient controlled for the tests and very good illustrations of contact imperfections and CPU hot spot area!

    I know you're glad to be nearing the end as that was a lot of time invested to completion.

    Congratulations sir, on one of the best reviews I've seen come from Toms yet!

    Ryan
    6