The Basics of CPU Heatsinks
A CPU heatsink is an accessory used to assist in cooling the CPU, creating a good heat dissipation environment for it. If the CPU heatsink is poorly chosen, the CPU will automatically lower its frequency to reduce heat in order to protect itself from overheating. This will result in a decrease in CPU performance. Therefore, choosing the right CPU heatsink is crucial.
Working Principle of a Heatsink
The heat transfer base makes close contact with the CPU. Through the thermal conduction mechanism, it transfers the heat generated by the CPU to the heatsink fins, and then the fan blows away the heat from the fins.
Factors Affecting Cooling Performance (Air Cooling)
1. Heat Transfer Efficiency
Heat Pipe Quantity and Thickness: More and thicker heat pipes effectively enhance heat conduction.
Heat Transfer Base Design: Heat pipe direct contact, copper base welding, and heat spreader plates each have their advantages, affecting heat transfer efficiency.
Fins and Heat Pipe Junction Process: The process of joining fins to heat pipes, such as pin-fin or reflow soldering, directly impacts the smoothness of heat transfer.
Thermal Paste: High-quality thermal paste fills micro-gaps and improves heat transfer efficiency.
2. Fins and Air Contact Area
The number and arrangement density of fins determine the surface area in contact with air. The larger the contact area, the better the heat dissipation.
3. Airflow
The higher the airflow, the better the cooling performance. Fan speed and design directly affect airflow, but a balance must be struck between noise and cooling efficiency.
By optimizing these factors, heat dissipation performance can be significantly improved, ensuring stable operation of the device.
Heat Transfer Efficiency:
The efficiency of heat transfer is crucial for cooling performance. The following four factors affect heat transfer efficiency:
Number and Thickness of Heat Pipes: The more heat pipes, the better. Generally, 2 pipes are acceptable, 4 are sufficient, and 6 or more pipes indicate a high-end cooler. Thicker copper pipes are better (most are 6mm, but 8mm pipes are also available).
2. Check the Heat Transfer Base：The base must be perfectly flat to ensure full contact with the CPU. If the base is uneven, no matter how many heat pipes there are, it won’t be effective. Therefore, the quality of the base craftsmanship must be absolutely precise.
Three Types of Heat Transfer Bases
Heat Pipe Direct Contact
This is the most affordable option. It ensures flatness by compressing and polishing the heat pipes, but this can make the pipes very thin at the bottom. Over time, this can lead to uneven surfaces, reducing thermal conductivity.
Copper Base Welding
The copper base is meticulously polished to a mirror-like finish and fully wraps the heat pipes. This solves the two major drawbacks of heat pipe direct contact. Most high-end coolers now use this type of base.
Heat Spreader Plate
Coolers with heat spreader plates are rare, but they are more common in high-end laptops. A heat transfer fluid is added to the base, which evaporates upon heating and evenly distributes the heat across the entire base, providing better thermal efficiency.
Thermal Paste
Due to manufacturing limitations, the base of the cooler and the CPU can never have a perfectly flat contact surface (even if it looks flat, magnification reveals imperfections). Thermal paste with a high thermal conductivity is applied to fill these gaps and improve heat transfer. Since thermal paste has much lower thermal conductivity than copper, only a thin, even layer is needed. Applying too much paste can actually hinder heat dissipation.
Typical thermal pastes have a thermal conductivity coefficient between 5-8, with premium pastes reaching 10-15.
Heat Sink Fin
Fins play a crucial role in dispersing heat into the air. Therefore, the key factor is the contact area between the fins and the air. In other words, the more fins there are, the better the cooling performance.
Additionally, since heat pipes are interspersed between the fins, the process used to join them also affects thermal conductivity efficiency.
In the reflow soldering process, a reserved hole near the heat pipe is used for internal welding.
The pin-fin process involves fins surrounding the heat pipe.
The reflow soldering process, as the name suggests, involves welding the heat pipes and fins together. It is more expensive but offers greater durability and strength.
The pin-fin process, also known as “pin insertion,” involves directly inserting the heat pipe into the fins. This method is cost-effective but requires high precision in workmanship and technique. If the insertion is done well, the fins stay securely in place; if done poorly, the fins will loosen quickly, significantly affecting thermal conductivity. Therefore, it is recommended to choose well-known mainstream brands that offer both affordable prices and guaranteed quality.
Fins and Air Contact Area
Fins are responsible for heat dissipation. Their job is to release the heat carried by the heat pipes into the air, so they must maximize their contact with the air. Some manufacturers design small protrusions to increase the surface area of the fins as much as possible.
Airflow
Airflow refers to the total volume of air a fan can move per minute, usually measured in CFM (cubic feet per minute). The larger the airflow, the better the cooling performance.
Other important fan parameters include: speed, air pressure, blade size, and noise level. Most modern fans come with PWM (Pulse Width Modulation) for intelligent speed adjustment, but the main factors we need to focus on are airflow and noise.
Types of Air Cooling Heatsinks
There are three types of air cooling heatsinks: passive cooling (fanless design), tower-style, and down-draft style.
Since the mounting brackets for AMD and Intel platforms are different, it’s important to check which platform the heatsink supports before purchasing. Most heatsinks support both platforms.
The brand of the Heat Sink
1. Passive Cooling
This is essentially a fanless heatsink that relies entirely on airflow to dissipate heat from the fins.
Advantages: Completely silent.
Disadvantages: Poor cooling performance, suitable only for platforms with minimal heat output (most of our smartphones use passive cooling, which may not even be as effective as passive cooling in some cases).
2. Down-draft Cooling
This heatsink has a fan blowing downwards, which not only cools the CPU but also helps cool the motherboard and memory. However, its cooling performance is slightly worse, and it can disrupt the airflow inside the case. It’s suitable for low-power platforms, and because of its compact size, it’s ideal for small form-factor cases.
3. Tower-style Cooling
This heatsink stands tall like a tower, hence the name. It blows air in a single direction, ensuring the airflow inside the case remains undisturbed. The larger size of the fins and fan results in better cooling performance. However, it doesn’t cool the motherboard and memory, so case fans are needed to assist with cooling.
Note: Some particularly large tower-style heatsinks may block memory slots due to poor design. It’s advisable to check with customer service before purchasing.
Summary
The heatsink itself isn’t expensive, and air cooling is the most cost-effective and safe option.
The cooling performance of a heatsink largely depends on its craftsmanship. Heatsinks from lesser-known manufacturers may have many heat pipes, but poor workmanship makes them ineffective. It’s recommended to buy from reputable brands to ensure quality.
When selecting a heatsink, be sure to check your case’s height limitations and supported platforms.
