Thermal Grizzly Kryonaut vs. Paste X (pre-series) in the thermal paste test: Changing of the guard after 10 years?

Important note

You will soon be redeemed, but the following still applies: The chart graphics in these first tests are still static graphics, but I will also use interactive graphics later, analogous to the fan bank at that time. But that still has to be programmed first.

The thermal resistances _Rth

Let’s start with the most important aspect, the thermal resistance _Rth. The most important property of _Rth is that it correlates nicely linearly with the layer thickness, while the thermal conductivity describes a completely different curve and remains anything but linear. I test the two pastes from Thermal Grizzly against the TF8 from Thermalright as the front runner and the Apex from Alphacool, which is a real long runner over many months in my applications. This means that there are several different solutions and orientations, whereby the Kryonaut is not really for long-distance running on very hot plates. But more on that later.

We are interested in layer thicknesses of 200 µm and less on the CPU, and usually 100 µm and less on the GPU, depending on the bending. Everything else is really for the gallery. Some manufacturers also specify the pure, idealized bulk value here, but this is completely unrealistic. The Thermalright TF8 was the best paste so far, even if you need medium-high skills to apply it. However, the Thermal Grizzly Paste X is hardly any worse, but is much easier to apply. Even without an applicator. That’s why it’s more or less a draw for me, especially as (almost) everything below 50 µm is irrelevant anyway. But here you can already see the secret of Kryonaut’s success with users, which is hardly inferior to the viscous pastes below 100 µm and is much easier to apply.

I now have the relevant layer thicknesses from 200 to 50 µm as a bar chart for _Rth comparing the pastes:

Control curve of Rth in the TIMA analysis

In the data interface, you can check the determined values again and deselect the deviating values (here everything from 25 µm downwards) for the determination. First for the cryonaut:

And now once again for the Paste X:

Minimum possible layer thickness

But at least I wanted to know how far you can go with proper pressure. I could have pressed the whole thing with 300 N, but then nothing would change. But what minimum layer thicknesses can still be achieved? The approximately 7 µm of the Kryonaut is really good, but is only finally achieved after a few minutes. The paste therefore needs a certain amount of time for a “burn-in”, in this case displacement. This paste started at 9. The more viscous Paste X is on a par with the even more viscous TF8 from Thermalright.

Interface Resistance

What also seems interesting is the contact resistance, in our case the interface resistance. Here you can see how well the surface of the paste “clings” to the contact surfaces (IHS, heatsink). These values are also easy to compare and meaningful, as they are always the same calibrated reference blocks. Coarser degrees of grinding or a less favorable microstructure can be just as much a negative factor, which then influences the effective thermal resistance and thus also the conductivity, as too low temperatures and too high a viscosity. Anything below 20 is acceptable and the top class starts at 10.