CPU Cooler cooling principle

2024-06-17 17:29:57

At present, CPU radiators are mainly divided into air cooling and water cooling, among which air cooling is the mainstream for the general public, and water cooling is used by high-end players. Below, let's first talk about the importance of CPU radiators. If the computer heat dissipation is poor and the CPU temperature is too high, in order to protect itself from being burned, the CPU will first automatically reduce the frequency to reduce heat, which will cause the computer performance to decline. Secondly, if the temperature is too high after the frequency reduction, the CPU will automatically trigger the computer to crash to protect itself, so it is still necessary to ensure good heat dissipation.

I. Working Principle of radiator 微信图片_20241009143222

The heat transfer base is in close contact with the CPU, and the heat generated by the CPU is transferred to the cooling fins through the heat conduction device, and then the fan blows away the heat on the fins. There are three types of heat conduction devices: 微信图片_20241009144504

1: Pure copper (pure aluminum) heat conduction.

This method has a relatively low heat conduction efficiency, but the structure is simple and the price is cheap. Many original radiators are this method.

2: Thermal copper tube: It is still the most commonly used method now. Its copper tube is hollow and filled with a thermal conductive liquid. When the temperature rises, the liquid at the bottom of the copper tube evaporates and absorbs heat. After transferring the heat to the heat sink fins, the temperature drops and condenses into liquid, which flows back to the bottom of the copper tube. In this way, the thermal conductivity is very high, so most of the current radiators are in this way.

3: Water cooler: It is what we often call water cooling, which is divided into integrated water cooling and split water cooling. It is water that takes away the heat of the CPU, and then the high-temperature water is blown away by the fan when passing through the tortuous cold row (the structure is similar to the radiator at home), and becomes cold water for recirculation.

II. Factors affecting heat dissipation

Factors affecting heat dissipation

The efficiency of heat transfer: The efficiency of heat transfer is the key to heat dissipation. The factors that affect the efficiency of heat transfer are the following four points.

1: The number and thickness of heat pipes: The more heat pipes, the better. Generally, 2 are so so, 4 are enough, and 6 or more are high-end radiators; the thicker the copper pipe, the better.

2: Process of heat transfer base: There are three types: direct contact of heat pipe, copper bottom welding, and heat spreader.

3: Thermal grease: Due to manufacturing process problems, it is impossible to have a completely flat contact surface between the radiator base and the CPU (even if it looks flat, you can see unevenness under a magnifying glass), so you need to apply a layer of silicone grease with a higher thermal conductivity to fill these uneven places to help conduct heat. The thermal conductivity of silicone grease is much lower than that of copper, so just apply a thin layer evenly. If it is applied too thickly, it will affect the heat dissipation. The thermal conductivity of general silicone grease is between 5-8, and there are also very expensive ones with a thermal conductivity of 10-15.

4: The process of the junction between the heat sink fins and the heat pipes; the heat pipes are inserted between the fins to transfer heat to the fins, so the processing technology of their junction will also affect the thermal conductivity.

5: The contact area between the fins and the air. The fins bear the heavy responsibility of dissipating heat. Its task is to send the heat sent by the heat pipe into the air, so the fins must be in contact with the air as much as possible. Some manufacturers will carefully design some bumps to increase the surface area of the fins as much as possible.

6: Air volume. The air volume indicates the total volume of air that the fan can send out per minute, generally expressed in CFM. The larger the air volume, the better the heat dissipation. The parameters of the fan also include: speed, wind pressure, fan blade size, noise, etc. Now most fans have PWM intelligent speed regulation, and what we need to pay attention to is air volume, noise, etc.