Wondering if you should replace the stock thermal paste in your PC with an aftermarket paste? We can help!
Thermal paste is an important part of removing heat from your CPU. As the thermal interface between the CPU heat spreader and the heat sink, a poorly performing paste can limit the efficiency of heat removal.
Computer enthusiasts often wonder if the paste that comes preinstalled with their CPU/heat sink combination is “good enough” or if they should replace this “stock” paste with an aftermarket product, of which there are many to choose from.
In order to answer this question, we’ll look at a few different properties of thermal paste, including what it’s made of, how it performs, and how well it holds up over time.
Should I Replace My Stock Thermal Paste With An Aftermarket Paste?
Generally, even the worst performing paste probably isn’t going to make a difference in the health of your CPU. The more important factor is how durable the stock paste is, as paste that separates out or dries up becomes much less effective at conducting heat. When that happens, your CPU’s health could be in jeopardy. For this reason, most experts will recommend that you change out your stock thermal paste to an aftermarket paste after 6-12 months.
P.S. – Check out our recommendations on which thermal pastes to use and which to avoid.
The main problem with stock thermal paste is that you don’t know what it is. In most instances you won’t know how its performance compares to any of the aftermarket products available.
That recommendation comes with a caveat though, which is how often you upgrade your computer. If you upgrade every year or two, it’s probably not worth the time and effort to change the paste.
The reason is this: even if the stock paste were to degrade enough over 6-12 months to start making your CPU run hotter, it still takes time for your CPU to suffer any ill affects from those elevated temperatures.
If you use your computer for gaming, video editing, or other CPU-intensive tasks, this might be a valid concern, but if you’re a more casual user it’s pretty unlikely to matter.
If, on the other hand, you tend to keep a computer for 5 years or more, it probably makes sense to change pastes. You’ll have peace of mind knowing exactly what paste is in your system, and you’ll have the opportunity to pick up a few degrees Celsius of performance improvement.
We also have a guide to thermal paste lifespan where we make some additional recommendations.
If you’re still on the fence about what to do, consider installing software to monitor the temperature of your CPU. You can set thresholds to alert you when your CPU gets hotter than you’d like. That way if you see a problem you can always make the decision to upgrade your paste.
Many users also enjoy simply monitoring their CPU temperature; when it comes to computer systems, more information never hurts!
Materials & Composition
Thermal paste is basically made of two components: (1) a binding agent, and (2) thermally conductive material mixed into the binding agent.
The binding agent is, at its most basic level, a mixture of zinc oxide and silicone. The purpose of the binding agent is to act as a vessel for the thermally conductive material, distributing it evenly while giving the paste structure and proper viscosity.
Nowadays, the binding agent is hardly ever just zinc oxide and silicone, though. Most manufacturers add other ingredients to the mix to differentiate their brand and modify the properties of the paste, making it more or less viscous, giving it different colors, etc.
The materials used in the binding agent can also affect the durability of the paste, but we’ll talk more about that later.
The thermally conductive material used by manufactures varies widely. Aluminum is common, as are various metal oxides. The well-known Arctic Silver brand adds – you guessed it – silver to its paste.
Copper was once a popular ingredient but has decreased in popularity.
Other more exotic ingredients include graphite and even carbon nanoparticles, though pastes that use these tend to be quite pricey.
While materials do vary widely, for the vast majority of pastes the biggest differentiating factor is how much silicone is used.
While silicone is an inexpensive binder, it does come with some problems, the chief one being spread. Spread refers to silicone’s tendency to “spread out” over the surface it’s applied to. This can create a mess when applying the paste and it can also make it difficult to achieve the appropriate level of thickness and coverage.
For this reason manufactures often use other materials to combat spread. In some instances they eliminate silicone altogether.
Silicone also has an effect on the next topic we’ll discuss: durability.
Another detrimental property of silicone is oiling. Over time, silicone tends to separate out from the base components in the paste and “ooze” away. This leads to degraded performance, either through a decrease in thermal conductivity or simply because there is no longer enough physical material to be effective.
Sometimes, if you squeeze paste out of an old tube, you will notice that it has separated into a clear oily substance and other, more solid compounds; this is oiling in action. Oiling can also happen after the paste is applied in your system. It is therefore a chief factor in a paste’s durability.
This is one reason why it’s generally recommended to replace even the highest quality pastes after 1-3 years. From all this we can draw the logical conclusion that pastes with a higher silicone content are more prone to oiling and are therefore less durable.
Aside from the known phenomenon of oiling, not a lot of rigorous testing and research has been conducted on the durability of different thermal pastes.
Suffice it to say that durability does vary and will affect the performance of your paste over time.
Right off the bat, we’ll say that performance doesn’t vary as much as you might expect, and the performance difference between many brands is extremely similar. The reason for this is something that may surprise you: there are actually only a few manufacturers of thermal paste. All of the other brands out there are third parties who take the base recipe and add other ingredients to it to slightly alter its properties.
These slight alterations in properties lead to slight differences in performance. For this reason, many experts view the difference in performance between the stock paste that comes with your computer and aftermarket pastes to be less significant than many enthusiasts might assume.
While the maximum recommended operating temperature varies depending on the CPU, a good rule of thumb is 80C. Tests conducted with the most widely-used, typical cooling setups show that with the worst performing thermal pastes, CPU temperatures reached about 62C.
With the best performing pastes, CPU temperatures reached about 58C. That’s a difference of only 4C. What this effectively means is that as long as you have any thermal paste installed between your CPU and heat sink, you really have little to worry about in terms of how the brand of paste will affect your system.
To take things a step further, tests have even been conducted using toothpaste in place of actual thermal paste. The results? The maximum CPU temperature reached just over 71C. That’s still well below the danger zone for virtually any CPU on the market.
Without making any claims as to its durability, we must repeat: even toothpaste will adequately cool your CPU!
There are other changes you can make to your cooling system that will have a similar effect on maximum temperature to changing the paste, such as using a water cooling system or using liquid metal in place of thermal paste, but there is one thing that swamps out the performance difference of any of the other modifications: correct mounting of your cooler.
In a typical cooling setup, the heat sink sits on top of the CPU case. On top of the heat sink sits a cooling fan. The cooling fan has some form of fastening mechanism that secures it to the motherboard, thereby sandwiching the heat sink between it and the CPU.
This creates a tight mechanical coupling between the CPU, thermal paste, heat sink and fan which allows for maximum efficiency of heat transfer.
Typically the fastening mechanism is one of two things: (1) clips or (2) screws. Both of these mechanisms work quite well in establishing the correct mounting pressure to adequately cool your system; the danger comes when they are incorrectly used.
An improperly mounted cooling system can easily make your CPU run 10C-20C hotter than it otherwise would. When comparing this to the maximum temperature difference between different thermal pastes of 4C, the significance is evident.
If your cooler mounting system uses clips, make sure they are properly locked down.
If it uses screws, make sure they are fully tightened. Make sure the fan sits flush against the heat sink.
If some other fastening method is used, make sure you understand it and secure everything properly.
After reading this article you should have a stronger opinion of how you feel about stock vs. aftermarket thermal pastes. In the end, your decision will likely hinge on how long you keep a computer and how much control you like to have over every aspect of your system.
Regardless of what you decide, we can all probably agree to keep the toothpaste away from your CPU!