Thermal paste, just like many other products has a limited shelf-life. Most thermal paste products expire after three to five years; provided that the product is stored in optimal conditions.
However, saying how long it takes for thermal paste to go bad is not as easy given the wide variety of brands available; Created by different manufacturers, using different ingredients and formulations. To further complicate the situation, it is widely believed that even after the passage of its expiration date, thermal paste can continue to be useable for many years, given proper storage.
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What Is Thermal Paste?
Simply put, thermal paste also known as thermal gel, thermal grease or thermal interface material, is the white-grey pasty substance found at the bottom of heat sinks and on top of the CPU.
The main purpose of thermal paste is to improve the dissipation of heat from the CPU – To cool the temperature of the CPU. Thermal paste is applied between the contact surfaces of the CPU and the heat sink. Thermal paste facilitates better conduction of heat from the CPU to the heat sink, especially when the computer is under load, by ensuring that there are no hidden pockets of air between their contact surfaces.
Air is a bad conductor of heat, and any air pockets between the CPU and the heat sink, no matter how minute, can significantly hinder heat dissipation; potentially leading to thermal throttling and damage to the delicate components therein.
Thermal paste not only fills up any air pockets, even microscopic ones, between the CPU and heat sink contact surfaces, but also promotes the transfer of heat.
Common Ingredients Found In Thermal Paste
As previously stated, the shelf life of thermal paste products varies with the ingredients used. With that in mind, there are three main types of thermal pastes as defined by the type of thermal compound used.
Types of Thermal Pastes
Metal-Based Thermal Pastes
Metal-based thermal pastes are normally made of solid metal particles (including silver and aluminum). Given the highly conductive nature of metals, these compounds are considered to be great at heat dissipation.
Their efficiency and effectiveness is demonstrated by the fact that computers using this type of thermal paste have been proven to run a few degrees cooler than those featuring a ceramic based compound.
On the downside, metal based thermal pastes (especially those made from silver) tend to be more expensive. More importantly, since metals are good conductors of electricity, using these pastes introduces a risk of short-circuiting computer components if the paste spills over to the metal contacts on the motherboard.
Ceramic-Based Thermal Pastes
Ceramic-based thermal pastes are made of a silicone suspension containing ceramic powder. Zinc oxide and aluminum oxide are some of the most common ingredients in ceramic powder. The relatively lower cost of silicon dioxide makes it one of the main ingredients in cheap, generic thermal paste products.
Ceramic based thermal pastes are widely used due to their affordable nature. Furthermore, their poor electrical conductivity means that they don’t present any risk of short-circuiting computer components even if they find their way to the motherboard contacts.
However, they are not as effective as their metal-based counterparts when it comes to cooling your computer, falling short by a couple of degrees according to available test data.
Silicon-Based Thermal Pastes
While they may not be as effective as the two previously described options, silicon-based thermal pastes are very easy to use. They normally come pre-applied on thermal pads, which are designed to be positioned in between the contact surfaces of the heat-sink and CPU.
These thermal pastes are normally found on stock CPU coolers from brands such as AMD and Intel.
How To Properly Store Thermal Paste
Even though thermal paste products do have an expiration date, they can be used effectively, for many years; provided that they are stored correctly.
Generally, the only time that a thermal paste can be considered to have gone bad is when the contents have turned watery, clumpy, or have separated. However, if the paste is still smooth and consistent, it can still be used.
Here are some storage tips you can follow to keep your thermal paste (regardless of whether it has been opened or not) in usable condition, for as long as possible.
Keep Things Tight: Start by ensuring that cap on the thermal paste syringe is tightly locked in place. You can even go a step further and place the syringe in a zip-lock bag, for added protection.
Store in a Cool Dry Place: Find a cool dry place to store the thermal paste, away from any sources of heat. Consider placing the syringe in a container to protect it from circulating air which may be hot and/or humid. Thermal paste should always be stored away from direct sunlight.
How Often Should You Apply Thermal Paste?
Once it’s properly applied and cured in place, thermal paste can continue working for years. Most people will have replaced their computer before the paste starts losing its effectiveness. However, you can re-apply it in any of the following situations:
• During Maintenance: You should apply thermal paste every time you detach the heat sink from the CPU. This can be whenever you are performing upgrades, maintenance or cleaning the computer, after extended periods of use – normally years.
• On a New System: Manufacturers may apply thermal paste sparingly, as a means of lowering their production costs; applying more thermal paste before you start using a computer can help enhance cooling (and performance).
• Regular Overheating: You can also apply thermal paste on your computer’s CPU if you notice that the machine’s temperature has been constantly increasing for no apparent reason.
Thermal paste plays an important role in keeping your CPU from overheating, when under load, preventing any related damage or performance issues. While thermal paste products do come with an expiry date, normally set between 3 to 5 years after the production date, they are perfectly useable many years after, with proper storage.