Results and conclusion
The second round will be especially interesting for people who want to find the best solution for a standard use. The winner is a big surprise. Gelid, Noctua, Phobya, Reeven, SilentiumPC, Thermal Grizzly or Zalman? We can give away that it is not an expected favourite this time. We enjoyed a nice competition in the middle category, where it takes a lot to keep making a difference. We also tested OEM paste from Scythe as a bonus.
The list of thermal compounds + test procedures
The alphabetical order of tested samples will be familiar to you from the previous part. It will be easy for you to find a particular paste in every picture and in the sampler. The sheet contains 13 entries again. Therefore, the 14th drop on the desk, Scythe compound, can be a bit confusing because you cannot buy it separately. It only comes with the Scythe coolers.
| Manufacturer and model | Specified parameters from the manufacturers’ site | Udávané parametre z webu výrobcov | Udávané parametre z webu výrobcov | Udávané parametre z webu výrobcov | Price | ||
| Thermal conductivity | Viscosity | Density | Operating temperatures | Quantity | Average price | ||
| Thermal conductivity | Viscosity | Density | Operating temperatures | Quantity | Average price | ||
| Gelid GC-Extreme | Gelid GC-Extreme | 8.5 W/mK | 85 Pa·s | 3.73 g/cm³ | N/A | 3.5 g | 8,50 eur |
| Gelid GC-Pro | Gelid GC-Pro | 7 W/mK | 170 Pa·s | 2.8 g/cm³ | N/A | 5 g | 7 eur |
| Noctua NT-H1 | Noctua NT-H1 | N/A | N/A | 2.49 g/cm³ | -50–110 °C | 1.4 ml | 8,50 eur |
| Phobya HeGrease Extreme | Phobya HeGrease Extreme | 8.5 W/mK | 85 Pa·s | 3.73 g/cm³ | N/A | 3.5 g | 8,50 eur |
| Phobya HeGrease Standard | Phobya HeGrease Standard | 6 W/mK | 85 Pa·s | 2.5 g/cm³ | N/A | 3.5 g | 5 eur |
| Phobya NanoGrease Extreme | Phobya NanoGrease Extreme | 16 W/mK | 85 Pa·s | 2.5 g/cm³ | N/A | 3.5 g | 11 eur |
| Reeven RT-Pro | Reeven RT-Pro | N/A | N/A | N/A | N/A | 5 g | 8,50 eur |
| SilentiumPC Pactum PT-1 | SilentiumPC Pactum PT-1 | 4 W/mK | N/A | 2.5 g/cm³ | -50–240 °C | 4 g | 4 eur |
| SilentiumPC Pactum PT-2 | SilentiumPC Pactum PT-2 | 5 W/mK | N/A | 2.67 g/cm³ | -40–240 °C | 4 g | 4,50 eur |
| Thermal Grizzly Aeronaut | Thermal Grizzly Aeronaut | 8.5 W/mK | 110–160 Pa·s | 2.6 g/cm³ | -150–200 °C | 3.9 g | 8,75 eur |
| Thermal Grizzly Hydronaut | Thermal Grizzly Hydronaut | 11.8 W/mK | 140–190 Pa·s | 2.6 g/cm³ | -200–350 °C | 3.9 g | 9,7 eur |
| Thermal Grizzly Kryonaut | Thermal Grizzly Kryonaut | 12.5 W/mK | 120–170 Pa·s | 3.7 g/cm³ | -250–350 °C | 5.5 g | 15,50 eur |
| Zalman ZM-STG2 | Zalman ZM-STG2 | 4.1 W/mK | N/A | 2.88 g/cm³ | -40–150 °C | 3.5 g | 6,50 eur |
Most of the pastes in the second test have higher viscosity. The highest is proven for Thermal Grizzly Hydronaut which does not contain any silicone, and roughly 190 Pa·s in a cold state figures. On the other hand, the relatively thin Gelid GC-Pro will have less than the specified 170 Pa·s.
We managed to spread every paste evenly, but some were a challenge. However, not Zalman ZM-STG2, which used to be known for its “chewing gum“ consistency and tearing, probably due to inappropriate storage and drying silicone. This time it behaved like a different paste (tested on five samples). Noctua NT-H1 and SilentiumPC Pactum PT-1 are also excellently prepared for smooth spreading. Quite elastic NanoGrease Extreme is a bigger problem, especially HeGrease Extreme which sticks more to the applicator than to the heatspreader. In this case, it is more practical to use the drop method.
The heating element was overclocked Intel Core i7-5930K@4.4 GHz (on Gigabyte X99 UD4) with increased Vcore to 1.25 V. We simulated the burn in InterBurnTest (7500 MB). The waste heat was around 225 W. After the initial burn in, the tests took 300 seconds. We used high-flow industrial fans Noctua iPPC NF-F12 2000 and Scythe Fuma cooler, so five minutes should be more than enough for temperatures to stabilize. Temperatures can decrease a bit after several hours, which was the case of Arctic Silver 5, but it is a rare situation because most of compounds do not require a long-term burn in to provide the best results.
We used a smooth layer of 0.1 ml of paste for every application. We repeated every test twice (new installation included) to make sure that measured values match. The intake air temperature was 21 – 21.3 °C, ensured in our air-conditioned lab.
The second round will be especially interesting for people who want to find the best solution for a standard use. The winner is a big surprise. Gelid, Noctua, Phobya, Reeven, SilentiumPC, Thermal Grizzly or Zalman? We can give away that it is not an expected favourite this time. We enjoyed a nice competition in the middle category, where it takes a lot to keep making a difference. We also tested OEM paste from Scythe as a bonus.
Results and conclusion
The victory of Phobya HeGrease Extreme is a small miracle for several reasons. Its specifications do not predict it at all. Paradoxically, NanoGrease Extreme should be better, but it is not. And finally, HeGrease Extreme kind of pretends to be a rebrand of Gelid GC-Extreme which has also worse results. The lowest temperatures in the test were confirmed by testing of the second HeGrease Extreme sample.
The Kryonaut from Thermal Grizzly achieved the same temperatures, but the double price does not speak up for it. Compounds from this company are generally more expensive (Aeronaut and Hydronaut included), but they all maintain the excellent standard. The added value is not only a threaded cap with a sealing, but also a unique applicator attached to the neck of the syringe.
Noctua NT-H1 has also ended up very well. We would not buy it separately because of its price, but if you already got it together with the cooler, it does not deserve to be replaced. We emphasize this especially because such practice is not that unique. The same can be said about more expensive Scythe coolers too. Although the paste is not sold separately, it has excellent results.
This doesn’t apply to Zalman ZM-STG2 and Alphacool HeGrease Standard which does not share the benefits of its sibling. It is not a bad paste, but there are better candidates among cheaper compounds. For example, SilentiumPC Pactum PT-1. It has the same effectiveness as the MX-2, but the legendary model from Arctic still remains preferable for its price. And that is why it has earned our award for the best cost/effectiveness product, along with Phobya HeGrease which is the absolute winner with a really acceptable price.
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