Industrial paste vs. AliExpress and mainstream: DOWSIL TC-5550, Gelid GC-4 and Snowman MTGS in a thermal paste review of large tubes

Today I have the next three pastes from your wish list in the programme (many thanks to the donors from the community!) and was rather satisfied with the result (but not completely). It also lived up to expectations, because you get a lot of content for your money. The DOWSIL TC-5500 is a decent industrial paste from Dow Corning, but unfortunately (so far) you can only get it in individual bottlings from abroad. Or soon under a different name as a branded paste, so please be surprised. The Snowman MTGS is not yet so well known in this country but, like the Gelid GC-4, is already available in Germany. Or for a small price at AliExpress & Co.

An important foreword on “bulk thermal conductivity” and false marketing promises

I am now deliberately prefacing this with two quotes that not only speak to me from the heart, but also absolutely agree with my laboratory measurements. Conventional pastes cannot achieve much more than 4 to 5 W/(m-K) under the usual conditions on a GPU or CPU in terms of layer thickness, temperature and pressure. Because these quotes are honest and unfortunately correspond to reality, I will use this part from now on as a standard quote in all paste tests of all manufacturers and put it in front. You can’t bend physics.

For those who wonder how you can even arrive at figures above this limit, it should be noted that test conditions can certainly be adapted to achieve astronomically high figures. However, testing in a bucket has nothing to do with reality, even if a known measurement method is used. Without knowledge of the exact circumstances, such values are completely misleading and meaningless. You could give many suppliers credit for simply not knowing any better and just copying the OEM’s data sheets, but it doesn’t make misleading consumers any better.

Real long-term simulations (3000 hours in 1000 cycles up to 90°C) are not feasible in terms of the effort involved. That’s why I can only make predictions, but I want them to be understood as such. It is virtually impossible to make scientifically sound statements in just a few days. Yes, you can identify a trend and scale it as a forecast based on existing data, but this is not something that allows you to make really reliable statements. Therefore, I am sorry to say that I have to leave out this important point. However, as far as time permits, I will take community feedback into account and add the comments and long-term experience of third parties to the database as a note in due course, if it seems necessary. In both a positive and negative sense. However, this is a subjective value that has no place in a comparative database.

DOWSIL TC-5550

DOWSIL TC-5550 is a thermally conductive paste from Dow Corning specifically designed for cooling high-performance processors and other electronic modules, especially for systems with bare die architectures that require efficient heat dissipation. With a high (true) thermal conductivity of 5.0 W/mK and a low thermal resistance, this paste improves the heat transfer between the component and the heat sink, increasing the lifetime and reliability of the devices, as DOWSIL TC-5550 provides excellent resistance to pump-out effects and stability at high temperatures.

The easy application of this industrial paste, including by screen printing, and its solvent-free nature further contribute to the popularity of this material, which was even awarded an innovation prize in 2023. So lots of advance praise from the commercial sector, but let’s just let ourselves be surprised!

Gelid Solutions GC-4

At around 10 euros for 10 grams, Gelid GC-4 is a fairly inexpensive and thermally conductive paste which, according to the bottler, was developed for use in high-performance CPUs, GPUs and other critical applications. It is said to have an estimated thermal conductivity of around 8.5 W/mK (which it does not) and should remain stable even at extreme temperatures between -30 °C and 150 °C without hardening or losing its performance. The paste consists of a polymer matrix that acts as a binder for the thermal fillers, allowing for even distribution of the fillers and ease of application. Its viscosity helps to effectively close gaps between the heat source and the cooling solution, ensuring optimal heat dissipation. At least that’s what the marketing says.

Snowman MTG5 / MTG10

The Snowman MTG5 from AliExpress and Amazon is described as a thermally conductive paste with a high thermal conductivity of 14.3 W/mK. According to the marketing, it is silicone-based and contains metallic oxides with a fine particle size that help to effectively close the gap between the heat source and the heat sink. The usual, not particularly creative blah blah. Again, you can get the family pack of 10 grams of paste for under 10 euros. So it will be interesting to see how the two special offers fare against the tried and tested DOWSIL TC-5550

Technical data

Let’s leave the marketing aside and look at the technical data of these pastes. We can see that the information on thermal conductivity is missing or incorrect (red). The columns highlighted in green contain my measured values, the columns highlighted in gray contain the manufacturer’s specifications and the accessories

Further links and basics