Thermal paste comparison 2018

Purchase advice for thermal paste comparison or test 2018

  • Thermal paste (short WLP) connect CPU heat spreader with the metal body of the separate processor cooler. They allow the main processors, which are in some cases very hot, to ensure reliable heat dissipation and, in addition to the CPU fan, represent the most important cooling component. WLPs are also used to cool a graphics processor (GPU for short) in graphics cards.
  • A distinction is made between two types of WLP: on the one hand, non-conductive pastes made of silicone oil and metal oxides - less frequently graphites are also used as heat conductors. On the other hand, electrically conductive liquid metal thermal compounds are also offered.
  • In addition to the heat conduction properties, ease of use is an important buying criterion for the best thermal compounds. In particular, liquid metal pastes make higher demands on the user, but score points with better performance data. Important: Do not use liquid metals on aluminum heat sinks.

Thermal paste comparison 2018: 2018

Modern microprocessors are marvels of technology. Work in a confined space Millions of transistors and process billions of operations in the second. As the lines run fast times hot and thus threaten the functionality - especially the hard-working CPU in the PC.

Especially the central processing unit of a computer or a graphics card must Keep a cool head during operation, That's why in most PCs passive and active cooling elements combined. The passive cooling rib is connected to the main processor via thermal grease. In our purchase advice, we explain the key criteria of a thermal paste test and give you helpful tips, so you quickly find your perfect thermal compound test winner 2018.

1. Do I really need thermal grease?

Active vs. passive CPU cooling

CPU coolers are combination devices: On the one hand, an active fan ensures that the air heated by the CPU is removed. It should be periodically serviced and cleared of dust to allow proper air circulation. In addition to the actively forced air circulation, a metallic cooling rib passes on the waste heat of the CPU heatspreader to the ambient air, which is referred to as passive cooling.

The problem is simple, but not trivial. The current flowing through the conductors of the microprocessors produces a significant amount of waste heat that can not be sufficiently dissipated by the small chips themselves to the environment. They must therefore be cooled so that the miniaturized transistors and tracks are not damaged.

If you buy a complete PC, you will not see the cooling paste because it has already been applied to the appropriate place by the manufacturer or dealer. Here you must also be careful: Opening the PC case can void the warranty, as the Stiftung Warentest already noted. However, if you assemble a PC yourself, the Paste supplied with the CPU cooler and must be self-applied.

The thermal paste is applied between the CPU heat spreader (also heatspreader) and the metallic heat sink. The aim is to increase the area for heat dissipation. To ensure that the heat transfer between the CPU heatspreader and the CPU cooler heatsink is perfect, the thermal grease is used: it minimizes any unevenness between the two components so that there is no poorly conductive air between them.

Danger:Silicone-based thermal grease can dry! Although the process takes a long time, it can affect CPU temperature and performance. High fan noise can be an indicator of dried WLP. Small monitoring programs (benchmark tools) help you to monitor the temperature of your CPU. If you measure temperatures higher than those specified in the PC manual for a long time, you should renew the WLP. Even with a replacement of the CPU cooler, it definitely means: apply new paste.

2. What is thermal paste and what are the differences?

Thermal paste comparison 2018: 2018

Simple alternative: thermal pads are easy to apply and remove without residue. The thermal conductivity is currently lower than with pastes.

There are two WLP types available for heat transfer between CPU and cooler. They differ in the color and composition of the ingredients. Very often they exist Pastes of silicones mixed with metal oxides or with graphite, These WLP are electrically non-conductive and can be applied very easily.

However, the better results in terms of thermal conductivity achieve Liquid metal thermal compounds, you conduct heat up to 8 times better in the cooling fins. For comparison:

  • WLP with metal oxides or graphite have a thermal conductivity of 10 to 15 W / (m * k) and reduce the CPU temperature by about 2-4° C.
  • WLP with liquid metals have a thermal conductivity of 40 to 80 W / (m * k) and reduce the CPU temperature by about 4-10° C.

Given in units of watts per meter and Kelvin W / (mK), the thermal conductivity gives you information about the speed with which the thermal energy supplied can propagate within a solid, liquid or gaseous substance. Further information on the SI unit of thermal conductivity and its calculation can be found here.

In the following overview we summarize the most important properties of the two types for you:

Metal oxides or graphiteliquid metals
no electrical conductivity

can be easily distributed

Remains are easy to remove

low thermal conductivity

mixed with hard degradable silicone

very good thermal conductivity

very liquid form

no drying - no regular renewal

only very small amount needed

hard to remove again

not suitable for aluminum radiators

electrically conductive: risk of short circuit!

In addition to pastes, many brands also offer thermal pads. The cooling aids, which are also known as heat-conducting foils, are often electrically insulated and thermally conductive, like pastes mixed with metal oxides or graphite, and less frequently are non-insulated pads. They are only placed between cooler and CPU and can be removed easily. The ease of use is, however, compared to only moderate thermal conductivity.

Tip:Thermal pastes and pads are not toxic. However, for the sake of the environment you should handle the pastes carefully. Non-electrically conductive pastes use biologically poorly degradable silicones as carrier material. Liquid metal thermal compounds are mixed with gallium, indium or silver, for example. These metals are non-toxic to humans, but should still be disposed of in the trash.

3. Tips and tricks - What you should keep in mind when using thermal compounds

Thermal paste comparison 2018: comparison

Bottle instead of syringe: Many pastes are delivered in a small bottle. The brush for application is integrated in the screw cap.

If you want to install a new CPU or a new cooler in your PC, you need to use a WLP. In addition to the basic question - liquid metal or silicone + metal oxide or graphite - also the correct dosage and distribution plays a decisive role.

In general, less is more! The irregularities in the surfaces of CPU heatspreaders and aluminum or copper coolers are microscopic. Too much paste can also have an opposite effect and increase the temperature.

Therefore, you should apply a thin, liquid metal pastes only very thin layer. Many pastes are delivered in a syringe, so you can easily apply a suitable amount. Important: Remove the remains of the last applied WLP before applying the new one.

The simple way of applying: Apply a maximum of lens-sized amount to the center of the CPU heatspreader and press the cooler directly with great pressure. The distribution takes place via the contact pressure.

A better alternative: Spread the applied amount on the metallic substrate with a small brush or spatula. But especially with liquid metal pastes, make sure that nothing goes wrong. The electrical conductivity increases the risk of forming contact points that lead to a short circuit. The following video visualizes the process:

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Video Board: The LAST Thermal Paste you'll ever need??