You can’t eat it, how to apply thermal grease properly

▲ Thermal grease is an essential component in a CPU (Photo = Intel)

When asked, ‘What factors determine PC performance?’, CPU, GPU, RAM, etc. immediately come to mind. ‘Which parts are responsible for cooling?’ refers to air-cooled and water-cooled coolers and case cooling fans. However, it is difficult to answer the question ‘What can improve performance and cooling at the same time?’ The answer is thermal grease.

Thermal grease is used where the cooler heatsink is in contact with the CPU IHS (heat spreader).

So, how does thermal grease affect PC performance? Furthermore, what criteria should consumers use when choosing a product?

If you understand the ‘thermal conductivity concept’ of Thermal Grease, the criteria for product selection will arise naturally.

Thermal goose, why do you need it?

▲ Photo = Tomshardware guide
▲ Photo = Tomshardware guide

When the CPU and cooler are newly installed, it looks like they are in close contact to the naked eye. However, when viewed with a measuring tool such as a microscope, there is an intense gap between the CPU heatspreader and the cooler heatsink. In other words, if thermal grease is not used, CPU heat is transferred to the air in this gap.

The problem is that the thermal conductivity of air is very low at around 0.025W/mk. This is why the CPU temperature rises very high when the PC is started without applying thermal grease.

Conversely, if the thermal grease is applied properly, the air between the CPU HIS and the cooler heatsink is replaced by thermal grease. Thermal grease, which has a very high thermal conductivity than air, usually has a thermal conductivity of 8~14W/mk or more. Because of this difference, heat from the CPU is efficiently transferred to the cooler, which determines whether the CPU is cooled or not.

In other words, the thermal paste with high thermal conductivity replaces the air layer between the CPU heat spreader and the CPU cooler, so that the CPU heat can be smoothly carried to the CPU cooler heatsink. The same principle applies to GPU cores. GPU core is the same principle.

Want to lower the CPU temperature as much as possible? Check ‘Thermal Conductivity’

Various thermal greases are available in the domestic market and overseas online shopping malls.

If you want to put the price aside for a while and want to lower the CPU and GPU temperatures as much as possible, you can check the ‘thermal conductivity’. For example, Thermalright’s TFX has a thermal conductivity of 14.3 W/mk. On the other hand, considering that general thermal grease has specifications of 8~9W/mk, it has high thermal conductivity.

If you want such a high performance thermal grease, you can buy it after looking at ‘W/mk’, which is the thermal conductivity specification.

FYI, although the official spec is higher than 14W/mk, there is a product called ‘pump spec’ which has a lower actual performance. If the product is not from a famous manufacturer and the specifications are too high, it is recommended to check the reviews and benchmarks instead of buying it immediately.

Do I have to reapply grease unconditionally after using the PC for a long time?

I knew thermal grease was important. So when will you redistribute? There is no clear answer to the question, but in general, once every two to three years is recommended. Of course, if the CPU temperature is not too high even if you use more than that, you do not need to reapply.

The key is that if you use the PC for a long time, the thermal grease (solvent) hardens. This lowers the thermal conductivity and leads to an increase in the CPU temperature. In this case, you need to reapply the CPU thermal grease. Of course, since it is rare for general users to monitor the CPU, it is good to know the typical symptoms that occur when the CPU temperature rises.

Typical examples are cases where the speed of the CPU cooler rotates abnormally fast when using the PC, making a loud noise, or the throttling phenomenon occurs due to the high temperature of the CPU, causing the PC to slow down. The same symptoms apply to the graphics card as well.

If the cooling fan (CPU / GPU) does not malfunction after the symptom occurs, it is better to check if it is time to reapply the thermal paste.

FYI, it is recommended to visit a center rather than an individual for reapplying GPU thermal grease. If the GPU is arbitrarily disassembled, there may be problems with the product or A/S limitations.

Grease type, viscosity and application

Grease has different application properties depending on its viscosity. The higher the viscosity, the more cuddling (stiff) the application, and the lower the viscosity, the thinner it is applied. MX4 and MX5, which have established themselves as national thermals, are representative examples. Because of its good price, good thermal conductivity, and good spread, it is widely bought by general users.

For reference, MX-4 has a thermal conductivity of 8.5W/mk and a viscosity of 87Pas, and the official thermal conductivity of MX-5 has not been disclosed and has a viscosity of 55Pas. However, if you look at the benchmarks and reviews of both products, it is confirmed that they have almost the same performance.

Thermallite TFX has a high thermal conductivity specification of 14.3W/mk, but it is a very poor product. Official specifications regarding viscosity were not disclosed, but in my own experience of applying it, it was very stiff even with the provided scraper (spatula).

▲ Serin C&I officially distributes various grease of domestic thermal grizzly.
▲ Serin C&I officially distributes various grease of domestic thermal grizzly.

In general, the higher the viscosity, the higher the thermal conductivity. Therefore, TFX thermal grease, which is evaluated as high performance thermal grease, and Kryonaut by Thermal Grizzly, which is called ‘thermal bearr’, are bought more by users with PCs or performance overclocks higher than general consumers. Of course, the general consumer can buy it. However, it is not recommended due to its poor application.

▲ There is also a metal-type grease with very high thermal conductivity (Photo = official YouTube collaboration)
▲ There is also a metal-type grease with very high thermal conductivity (Photo = official YouTube collaboration)

If thermal grease is roughly divided into thickness and thinness, ie application properties such as viscosity, there are products with a very high thermal conductivity of 79 W/mk with 100% liquid metal.

However, being a liquid metal, it has the property of being conductive (conducting electricity). In addition, there is a disadvantage that the CPU serial number (label) can be erased when used with general thermal grease on the CPU heat spreader.

Therefore, it is mainly used for the CPU core and the surface that touches the IHS which is called ‘Duta’ (the act of removing the CPU IHS), which is used by some among over-miners, is applied to him.

Various application methods such as hub, X, etc, which is better?

▲ CPU temperature difference according to the method of applying thermal grease (Photo = YouTube MYPC)
▲ CPU temperature difference according to the method of applying thermal grease (Photo = YouTube MYPC)

If you mainly play casual games with a general mainstream PC, it is difficult to feel the temperature difference according to the method of applying the thermal grease. However, in high-performance PCs, especially in special environments such as overclocking, the coating method is also important.

Just as there are different types of thermal grease, there are also different application methods. Usually, an application is used as · (central dot) or X, and it is used in the form of ※ (billiard room) depending on the viscosity. Combining data such as foreign benchmarks and some YouTubers, the ‘request X’ method is generally recommended.

If the grease has high viscosity like TFX and Bear Thermal, it is also good to apply with ※.

How often do you use thermal grease? Check the presence of high capacity products at the time of purchase

▲ Depending on the thermal grease model, there are products with a maximum capacity of 50 g or more (Photo = Arctic)
▲ Depending on the thermal grease model, there are products with a maximum capacity of 50 g or more (Photo = Arctic)

When buying thermal paste, I usually buy a lot of 2g. 2g is the amount that can be applied approximately twice. If you are in an environment where you need to apply thermal grease frequently, or if you are a user who needs a lot of capacity as the replacement time approaches, buying a high capacity model is another option.

Depending on the product, there are products with a capacity of as little as 1g and as much as 50g.

If you operate an assembled PC or frequently change test PCs, it’s also a good idea to buy a capacitor-type thermal paste that has low thermal conductivity but has a large capacity and is cheap.

AMD CPU Design Completely Changed, How to Apply ZEN 4?

▲ Photo = Noctua
▲ Photo = Noctua

AMD ZEN4, scheduled for release on September 27, has a different CPU design than before. The CPU IHS (heat spreader) design has been changed, and if applied as before, thermal grease may leak into the container next to it.

In this regard, Noctua recommended the method of applying a central dot of 3 to 4 mm for socket-compatible AM5 CPUs. As the design of the CPU has changed, this factor is deemed to be reflected.

▲ The CPU die design and location changes slightly depending on the CPU core configuration (Photo = MSI YouTube)
▲ The CPU die design and location changes slightly depending on the CPU core configuration (Photo = MSI YouTube)

Also, the die may be different depending on the CPU core configuration. In the case of AMD, the location is determined by the CCD1 + CCD2 configuration, but Intel has a different die depending on the core configuration. This can change the sweet spot according to the CPU’s heating point.

Since the purpose of thermal grease is to conduct CPU heat to the cooler, understanding this principle and applying grease to the CPU could be of more help.

There are many thermal pastes on the market. It’s hard to buy without knowing, but easy to understand. So, if you know ‘thermal conductivity and viscosity’ when buying thermal paste, you can choose the product that suits you wisely.

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