Thermal Paste Round-up: 85 Products Tested

Thermal Paste: How It Works & How You Should Apply It

Convex & Concave Heat Spreaders

To make matters worse, heat spreaders are not merely rough, but due to the way they're manufactured, they aren't level, either. The following diagram exaggerates the problem for the purpose of illustration:

AMD’s heat spreaders are slightly higher in the center and Intel’s have higher edges. From our perspective, AMD's approach is better-suited for cooling. Due to the mounting pressure of the CPU cooler, the thermal compound is thinnest where most of the heat needs to be transferred. Thus, Intel CPUs deserve perhaps a touch more thermal paste, and you should take care that no air gaps form in the center.

How Thermal Paste Spreads Under Pressure

The following animation illustrates how thermal paste escapes to the sides when pressure is applied. Later, we’ll discuss the relationship between a paste’s fluidity (how "liquid" it is, the opposite of viscosity) and the maximum mounting pressure in detail. For now, let’s just say that a paste with low viscosity is more suitable for low-pressure mounting methods, like Intel’s push-pin method, than a "hard" paste.

The technical specifications of a thermal paste’s thermal resistance do not necessarily predict its real-world performance for a specific combination of CPU, paste, and cooler. A good heat sink can be crippled by a mismatched thermal compound. A good match between cooler and paste can achieve more than just blindly choosing an expensive thermal compound.

A Philosophical Debate: The Application Method

It’s tough to pick a technique for applying paste. Any method only works well if paste quantity and viscosity is absolutely correct for the particular application. In light of the hot-spot discussion, however, we believe that smearing paste on the whole CPU is quite pointless and a thing of the past. Instead, we want to focus on the particularities of the CPU, its heat spreader, the heat sink, and the mounting method (in particular the mounting pressure).

Brushes & Low-Viscosity Pastes

Liquid pastes like the Revoltec Thermal Grease Nano can be applied with a brush, and are consequently the easiest to use. However, low viscosity comes at the price of a high silicone content, which impacts thermal conductivity. These pastes typically fall to the bottom of our performance charts. When you try to apply semi-liquid pastes by brush, typically you wind up with too much, and that isn’t optimal, either.

Drop, Sausage Or Wall Painting?

Trying to spread a high-viscosity paste with a credit card is a fool’s errand. You'll waste a lot of time and won’t achieve a thin, smooth layer. Yes, you can try to put a latex glove on your hand and use your index finger. But even with this method, the risk of applying too much paste is significant, especially if you have no practice. The higher the viscosity, the less successful you can anticipate being trying to "paint the wall."

The Strip Method: It's All About The Sausage

When you imagine CPU die under the heat spreader, it may seem smart to put a strip of paste over that area. But 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.

When you apply the paste strip frugally, the result is better. Don’t worry too much about bare spots. The edges of the heat spreader don’t contribute much to thermal transfer anyway. If your cooler sports a back plate and applies lots of mounting pressure, the paste will spread further. As a rule of thumb, the lower the viscosity of the paste and the higher the heat sink's mounting pressure, the more your compound of choice will spread.

The Ideal Blob

The "drop" or "blob" method can be used by both newbies and enthusiasts, and it even works with high-viscosity pastes, assuming you are using a quality cooler that applies plenty of mounting pressure.

Don’t apply too little paste for fear of overdoing it. The compound might end up not covering the hot spot, hurting thermal conductivity and leading to an overheated CPU.

Take the type of cooler into account, too. An aftermarket heat sink with a back plate, which is screwed down, can tolerate less paste than AMD's "hook a clip and flip a lever" or Intel's "four push-pin" sinks. When you use pastes with higher viscosity, you want a cooler able to apply more pressure, and it's alright to use more paste. Of course, when we say more, we mean a little, not an extra-generous slathering.

The picture above shows a near-optimum spread; we wound up with a thin layer that completely covers the die. Since it didn’t reach the edges, we know we didn't use too much paste, and that it wasn't applied too thick. Beware of literally using a pea-sized blob. A paste ball about 2mm to 4mm in diameter should be enough; don’t use more than that! We're talking about a lentil-sized ball here.

Last But Not Least: Don’t Panic!

CPU manufacturers also believe in a less-is-more philosophy, as evidenced by their boxed coolers. For instance, AMD’s heat sink only touches about two-thirds of the heat spreader. The stencil-printed paste sports a high viscosity. It's almost solid, and it doesn't spread outwards (the sink's mounting pressure is relatively low). But this method obviously gets AMD’s blessing.

Why do we bring up this cheap boxed cooler? To allay fears and to encourage a healthy do-it-yourself spirit. Yes, two decades ago I also had my doubts about mounting aftermarket CPU coolers. But I encourage you to try it with an ounce of preparation, a sprinkle of can-do attitude, and a pinch of carefulness. Nothing will go wrong.

MORE: Best CPU Cooling

MORE: How To Choose A CPU Cooler

MORE: All Cooling Content

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  • AndrewJacksonZA
    *heavy breathing*
    I love these kinds of articles and in-depth super tests!! Thank you so much for all your time, effort and hard work, I appreciate it. I'm sure that I'm going to enjoy reading it.

    Um, do you guys still have a single page or "printable" view please?
    3
  • Yuka
    Oh, amazing article. I love it a lot.

    Maybe it's because I've used Artic Silver 5 for so many years, but for me it's the best all-rounder compound there is. Plus it's very cheap. I like it more than the MX-2 and MX-4 compound siblings people usually recommends. But I have to say, the "diamond" compounds are indeed better it seems. I had my doubts, but no more with these tests.

    Cheers!
    1
  • InvalidError
    Long story short: apart from esoteric TIMs, all pastes are practically as good as any other for typical uses when applied correctly. That really shouldn't surprise anyone as all pastes rely on the same principle of various particle sizes in silicon oil suspension getting crushed together.
    3
  • DarkSable
    Hang on, I'm sorry.

    Quote:
    Also, very cheap silicone-based solutions like Arctic MX-2 and MX-4, despite being easy to apply and affordable, aren't worth the trouble they cause later as they deteriorate.


    I work with MX-4 almost exclusively. Yeah, it's not $30 a tube, but it's also not "very cheap," are you kidding me? "Very cheap," is the Elmer's glue you sniffed as a kid, repackaged as thermal paste.

    I use MX4 specifically because it doesn't have a burn in period and because it lasts FOREVER.

    No, it doesn't deteriorate. I've seen reports a decade after the fact showing less than three degrees celsius difference from when it was first applied.

    So. Either you're biased because of ignorance, or both Artic's warranty and every long term test done before this has been lying. Gosh, lemme think which is more likely...

    Now, is something like MX4 the best thermal paste out there? Of course not. But it IS way better than a lot of the market, super easy to apply and maintenance-free, and very reliable. If you're going to be a snob about your thermal pastes, at least be accurate about it.
    3
  • zippyzion
    Well, I didn't see that result coming. They are almost all the same. So, why even bother picking? Just get the cheapest stuff from a reputable name. That's a little disappointing that doubling your money gains you a degree or two, at best.
    0
  • grimfox
    Within the article you talk about the considerations for GPU backplate for augmented cooling. Do you plan to do a review/article for products involved in that? I would be interested to know which thermal pads or shims or pastes you are using to augment GPU cooling. And to see a comparison of different products. I recently replaced a laptop GPU and redid the pads for that. The installation did involve a learning curve and finding products was not straight forward.
    0
  • JamesSneed
    Nice job on this article. Do more of this It helps the enthusiast community.

    Looking at your data Thermal grizzly Kryonaut wins as the best non-metal TIM except in low mounting pressure situations. it doesn't seem to matter as long as you have one of the decent pastes but its obvious there are a few to avoid like the Coolplast20 or Amasan T12 for example.
    5
  • FormatC
    @DarkSable:
    I'm using TIM since over 15 years, not only for Home PC's, but also in the industry. The major problem of this MX-4 are the long Burn-In time to get a better performance and the fast dry-out issue. As hotter a CPU or GPU works, as worse this grease performs (and is drying out). I does a lot of long-term runs with different products and especially this older products (not only from Arctic) were showing this typical behavior.

    If you prefer MX-4, why not? Use it. But please accept, that a test of different products over 4 years can show at the end a completely different picture. :)

    I get a lot of hardware (mostly VGA) with MX2- or MX-4 as replacement of the original TIM from other reviewers in rotation. And I have every time to replace this replacement with better (or original) products to get the original performance back. MX-2 on a VGA card is pure pain. Simply try one time another, better products and you will be surprised.

    @JamesSneed
    I have to take, what's in Germany on the market. All pastes were retail and not sponsored samples from the manufacturer. It was my idea to do this under real conditions. But I think it is possible to organize some stuff also from the US or Asian market.
    1
  • JamesSneed
    With Ryzen and more so Thredripper I wonder if those will impact application methods due to the multiple dies under the heat spreader? Seems you would want to make sure you have the area the dies are covered with TIM and that area is spread out more with those CPU's.
    1
  • AndrewJacksonZA
    A great article, thank you! :-)
    0
  • joz
    Interesting, I didn't expect my preferred TIM, Antec Formula 7, to do "poorly" as it did. But that's really only in comparison to the exotics. Compared to the standard TIMs, it is slightly above middle. However, of all the TIMs I've seen or used - the Formula 7 seems to have the best shelf-life. I had a few tubes of various other TIMs around - BeQuiet's included paste for the H7, and old bottle of Zalman (like...9500AT top of the game old), MX-4, and others. Of those, only the Formula 7 hasn't had any sort of separation or drying out issues. The same tube I've had for about 8 years now, and its still just as good as it was when I got it.

    Also, its one of the easiest to apply and get good coverage out of.
    0
  • FormatC
    @JamesSneed:
    This was really not easy to learn. I tried different methods with my chiller (to get at least one stable factor for a comparison in this tests). It is at the end more important to get the thinnest but perfect film without any bubbles and not the biggest possible area/surface. TR is soldered (thx for that) and the IHS is really stable. You need a good compromise between pressure and the amount of used TIM. Mostly is less better ;)

    My best friends are good torque screw drivers ;)

    2
  • mapesdhs
    Strange, I'm not seeing inline images for this article (FF 54.0.1).
    1
  • daglesj
    I would say if folks are concerned with things as trivial as 'paste burn in' then they really need to re-think their lives.
    -1
  • daglesj
    And yeah...images not showing.
    2
  • JamesSneed
    Anonymous said:
    @JamesSneed:
    This was really not easy to learn. I tried different methods with my chiller (to get at least one stable factor for a comparison in this tests). It is at the end more important to get the thinnest but perfect film without any bubbles and not the biggest possible area/surface. TR is soldered (thx for that) and the IHS is really stable. You need a good compromise between pressure and the amount of used TIM. Mostly is less better ;)

    My best friends are good torque screw drivers ;)




    Thanks for that.
    0
  • JamesSneed
    Anonymous said:
    I would say if folks are concerned with things as trivial as 'paste burn in' then they really need to re-think their lives.


    I'm not concerned so to speak but before I set my fan profiles up to keep my computer cool and quite under lower loads I do burn in the CPU with prime 95 for a couple hours just to make sure my temps are what they will be after a burn in. I like to Prime95 a new build to check stability, Overclock it, Prime 95 it, repeat until stable. Then I go in and tweak my fan profiles and other misc features(wait on that just in case I have to do a BIOS rest on OCing). Maybe its just me but how I do it.
    0
  • bit_user
    Thank you! I've been waiting for just such an update!
    0
  • JackNaylorPE
    Anonymous said:
    Oh, amazing article. I love it a lot.

    Maybe it's because I've used Artic Silver 5 for so many years, but for me it's the best all-rounder compound there is. Plus it's very cheap. I like it more than the MX-2 and MX-4 compound siblings people usually recommends. But I have to say, the "diamond" compounds are indeed better it seems. I had my doubts, but no more with these tests.

    Cheers!


    One of my disappointments w/ this article is that it leaves out the winner of the last 80 way test like this and that's Shin Etsu which as far as I have seen has the best performance / price ratio out there. My guess is because it's sourced directly from the manufacturer who caters to industrial customers rather than a vendor who buys from an OEM and repackages for the PC industry.

    https://archive.benchmarkreviews.com/index.php?option=com_content&task=view&id=150&Itemid=62&limit=1&limitstart=12

    Shin Etsu equaled AS5s performance in that last 80 way test but AS5 has 3 major disadvantages.

    a) It costs more.
    b) It requires 200 hours of curing time... at 8 hours a day, that's 3-1/2 weeks
    c) The last I will take from A5s home page and concerns potential mishaps.

    Quote:
    Arctic Silver 5 was formulated to conduct heat, not electricity.
    (While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)


    Shin Etsu is available from multiple sources for < $4

    It does seem to increase in viscosity over time when exposed to air. Not an issue on CPUs. But when ya doing a GFC card including both sides of thermal pads and both for the back plate and block at VRMs and memory on GFX cards, it can be an issue. Gelid Extreme is good here which is good as that's what is shipped with EK water blocks.
    1
  • AgentLozen
    This was a great article with a lot of information. I've been wondering about the specifics of thermal pastes and many of my questions were answered.

    I wish the author would have discussed what their favorite thermal paste to use was and why. The numbers seem to indicate that the Thermal Grizzly Kyronaut paste typically performed the best and was subjectively ranked high up in the usability category. So in conclusion.......... is this the paste that I should buy for my next PC? Or is there a reason I wouldn't want to? Similarly, the Titan Nano Blue consistently fell to the bottom of the charts. Should I avoid that paste at all costs. The article never really says.

    It may seem like I did a lot of complaining, but I want to reinforce that this article was very helpful. Thank you.
    0