Liquid Metal vs. Thermal Paste: Which One is Better?

What do you think of when you think of “liquid metal”? Lava? Magma? All close, but actually – liquid metal does exist as a stable compound! Metals like gallium and mercury, for example, are liquid at room temperature. Some of them are great conductors of heat and are therefore suitable to be used in computing – more specifically in place of thermal paste. But are they really better than thermal paste? Let’s find out.

Differences Between Liquid Metal and Thermal Paste

Let’s first differentiate between “liquid metal” and “thermal paste”. Thermal paste is actually a product name whereas liquid metal is a material, so we’re not comparing the two. What we’re comparing is liquid metal-based thermal paste and silicone-based thermal paste. Silicone derivatives are the most common compounds found in most thermal pastes. Silicone acts as a medium in thermal paste, holding metal compound particles (i.e. Zinc Oxide) in place and giving thermal paste its greasy properties.

In a metal-based thermal paste, there is essentially no medium. This means the metal itself acts as the gap-filler when applying the thermal paste. The liquid metal is a great conductor of heat but is also a great conductor of electricity. This gives it many advantages, but also a few risks. Let’s compare.

Liquid Metal-Based Thermal Paste

Pros

·        Amazing thermal conductivity (~70W/mk)

Cons

·        More complicated application process

·        Can potentially damage components

Let’s first explore liquid metal-based thermal pastes. If you’re unclear, thermal paste has 2 functions – the first is to be a good conductor of heat as most people already know, and the second is to be a gap-filler. The surfaces of your CPU and heatsink are not perfect. They have ridges and gaps where oxygen could get in and inhibit the transfer of heat. Thermal paste’s job is to fill that space instead.

As mentioned before, unlike their silicone-based counterparts, liquid metal-based thermal pastes don’t use a medium which allows the metal itself to fill the gaps between the CPU and heatsink where oxygen would normally seep in. This, on top of their all-metal composition, allows them to be much better conductors of heat, regularly measuring up to 70W/mK. However, most liquid metal-based thermal pastes use Gallium or a similar metal. These metals, in addition to being great heat conductors, are coincidentally great conductors of electricity.

At this point, you might be asking yourself “Well, what’s the problem with that? Computers use electricity right?” “Two birds, meet stone.”

Usually, you would be correct, but electricity is only useful in a computer if it flows the way you want it to, or rather if it interacts with the components in a specific way. A single drop of Gallium could draw an electrical current astray, leading it to short-circuit another component on the motherboard, and effectively rendering your entire motherboard… useless. How about that for risk and reward? And if that wasn’t enough, Gallium specifically reacts with aluminum, meaning if your CPU or heatsink is made of aluminum or the Gallium gets on an aluminum component, it could embrittle the aluminum and form an alloy.

Taking all this into account, the application process for liquid metal-based thermal pastes is a lot riskier and more specific than it is with silicone-based thermal pastes.

Silicone-Based Thermal Paste

 Pros

·        Cost-efficient (~$3/gram)

·        Easy to apply; no risk of damage to components

Cons

·        Lower thermal conductivity (5-10W/mK)

Unlike their liquid metal-based cousins, silicone-based thermal pastes are much more simple. In addition to silicone or silicone derivatives, silicone-based thermal pastes usually use a filler like Zinc Oxide – or a similar inorganic compound – as a thermal conductor. Some thermal pastes may also use organic compounds as fillers. However, these are usually less reliable and will degrade faster under heat.

Silicone-based thermal paste’s selling point really comes from… well… its selling point. Liquid-based thermal pastes can cost twice to three times what a standard tube of silicone-based thermal paste would cost. They’re simply more expensive to manufacture, thus leaving silicone-based thermal pastes as the victor when it comes to cost.

Secondly, the process to apply a silicone-based thermal paste is much more simple. If you know nothing about thermal paste or computers, you can simply put a dot of the thermal paste onto your CPU and go from there. If it spills out, the materials inside the thermal paste are generally not electrically-conductive so there’s no risk to your motherboard or any other components. Simply clean it up using a paper towel or specialized wipe and you’re good to go.

“But what about the cons?”

We say “cons”, but really thermal conductivity is only “lower” when compared to liquid metal which is a top-of-the-chain material. That’s like saying your desk lamp is inferior to an industrial-strength floodlight. While the statement is true, you probably wouldn’t want or need the latter in any practical scenario.

Which is the best for cooling a CPU/GPU?

 It depends. What do you want to achieve? Typically, silicone-based thermal pastes are more than enough for any task – gaming, video-editing, or running many applications at once. Liquid metal-based thermal pastes are used for extreme high-end builds or enthusiasts who want to push their processing and cooling to the absolute limit. This would mean overclocking your CPU or GPU and having a high-end air or water cooling setup.  

Other than your performance goals, another consideration is the risk of spillage. Recall that getting ANY liquid metal-based thermal paste onto your motherboard or other components is a huge risk. If you’re confident in your thermal paste application skills then liquid metal-based thermal paste may be right for you. However, even if you are a seasoned veteran, your thermal paste could spill on its own despite flawless application.

And as mentioned previously, silicone-based thermal pastes’ thermal conductivity is not as high as that of liquid-metal based thermal pastes. However, they are still the industry standard and can achieve phenomenal results. The simple fact is that despite the earlier floodlight analogy, the real performance difference between liquid metal-based thermal pastes and silicone-based thermal pastes is not that big.

Despite the advantages, we would still recommend a silicone-based thermal paste. For example, Kooling Monster KOLD-01 is a premium thermal paste, made with inorganic compounds, which can effectively cool your computer and help it reach its peak performance.