The CPU heat sink is an accessory used to assist the CPU heat dissipation, to create a good heat dissipation environment for the CPU, if the CPU heat sink is not selected well, the CPU will automatically reduce the frequency to reduce heat in order to protect itself from being burned out, which will lead to a decrease in CPU performance, so the choice of CPU heat sink is very important.
First, the working principle of the radiator
The heat transfer base is in close contact with the CPU, and through the heat transfer device, the heat generated by the CPU is transmitted to the heat dissipation fin, and then the heat on the fin is blown away by the fan.
There are three kinds of heat conduction devices:
① Pure copper (pure aluminum) heat conduction: This way of heat conduction efficiency is relatively low, but the structure is simple, the price is cheap, many original radiators are in this way.
② Thermal conductivity copper pipe: this is now the most commonly used way, its copper pipe is hollow, which is filled with a thermal fluid, when the temperature rises, the liquid at the bottom of the copper pipe evaporates to absorb heat, the heat is transferred to the heat fin after the temperature is reduced to condense into a liquid, flow back to the bottom of the copper pipe, so cycle, high thermal conductivity efficiency. So most radiators today are in this way.
Water: It is what we often say is water-cooled, strictly speaking, it is not water, it is a liquid with a high thermal conductivity. It takes away the heat of the CPU through water, and then the hot water is blown away by the fan when it passes through the curved cold row (the structure is similar to the radiator in the home), and becomes cool water and circulates again.
Factors affecting the heat dissipation effect (air cooling)
Efficiency of heat transfer:
The efficiency of heat transfer is the key to heat dissipation, and the factors affecting the efficiency of heat transfer have the following four points.
1. The number and thickness of heat pipes: the more the number of heat pipes, the better, generally 2, 4 enough, 6 and above is a high-end radiator; The thicker the copper pipe, the better (most of them are 6mm, and there are 8mm).
2. Heat transfer base process:
① Heat pipe direct contact: the base of this scheme is very common, and the general radiator of 100 yuan and below is this kind of. In order to ensure the smoothness of the contact surface with the CPU, the copper tube will be patted and polished, which makes the already thin copper tube thinner, and the uneven phenomenon will appear over a long time, affecting the thermal conductivity efficiency. Regular large factories will polish the copper pipe very flat, so that the contact area with the CPU is larger, and the thermal conductivity is high. Some of the copper pipes of the cottage manufacturers are uneven, resulting in some copper pipes that do not touch the CPU when working, so more copper pipes are just flower shelves.
② Copper bottom welding (mirror grinding) : the price of the base of this scheme is slightly more expensive, because the heat transfer base is directly made into a mirror, the contact area is higher, and the thermal conductivity effect is better. Therefore, the middle and high end air cooled radiators are used in this scheme.
③ soaking plate: This is a rarely seen program, the principle is similar to the heat pipe, but also through the liquid heat evaporation, and then cold liquefaction to transfer heat, this program heat conduction uniform efficiency is high, but the cost is high, so rare.
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 you look very flat, but you can see the uneven under the magnifying glass), so it is necessary to apply a layer of high thermal conductivity of silicone grease to fill these uneven places to help heat conduction. The thermal conductivity of silicone grease is much lower than that of copper, so as long as it is evenly coated with a thin layer, if it is too thick, it will affect the heat dissipation.
The general thermal conductivity of silicone grease is between 5-8, and there are also very expensive thermal conductivity of 10-15
Heat dissipation fin and heat pipe junction process: heat pipe is interspersed between the fins, to transfer heat to the fins, so the processing process of their junction place will also affect the thermal conductivity, the current processing process has two kinds:
Reflow welding: As the name implies, it is to weld the two together. This scheme costs more, but the thermal conductivity is good, and it is very firm, and it is not easy to appear the phenomenon of fin loosening.
② Wear fin: also called "wear piece" process. As the name suggests, it is to cut holes in the fins, and then use external forces to insert the heat conductive copper tube into the fins. This process has a low cost, although simple, but it is not easy to do well, because you have to consider poor contact, loose fins and other problems (if you are handy, the fins slide on the heat pipe, the thermal conductivity effect can be imagined).
The size of the contact area between the fins and the air
Fins bear the heavy task of heat dissipation, its task is to send heat from 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 convex points to increase the surface area of the fins as large as possible.
Air volume
Air volume indicates the total volume of air that the fan can send out per minute, which is generally expressed by CFM. The more air, the better the heat dissipation.
The parameters of the fan are: speed, wind pressure, fan blade size, noise, etc. Now most fans have PWM intelligent speed regulation, we need to pay attention to the air volume, noise and so on.
Three, the type of air-cooled radiator
There are three types of air-cooled radiators: passive cooling (fanless design), tower type, and downward pressure type.
The difference between three types of air-cooled radiators:
1. Passive heat dissipation: It is actually a fanless version of the radiator, which relies on air circulation to take away the heat on the fins. Pros: No noise at all. Disadvantages: poor heat dissipation performance, suitable for a particularly small heat generation platform (our mobile phones are almost passive heat dissipation, even less than passive heat dissipation).
2. Down-pressure heat dissipation: This radiator fan is blown downward, so it can also patronize the motherboard and memory strip heat dissipation while taking into account the CPU heat dissipation. However, the heat dissipation effect is slightly poor, and it will disturb the chassis air duct, so it is suitable for the platform with small heat, and because the size is small and does not take up space, it is the Gospel of the small chassis.
3. Tower heat dissipation: This radiator stands tall as a tower, so the name tower heat dissipation. This radiator blows one-way, does not disturb the air duct, and the fins and fans can be relatively large, so the heat dissipation performance is the best. However, the heat dissipation of the mainboard and memory cannot be taken into account, so the fan on the chassis is required to assist.
Although the number of heat pipes is very important, but the heat-absorbing base work must be good enough, if the work is not smooth, no more heat pipes are useless, so the radiator is more work. When choosing a radiator, be sure to pay attention to: the height of the chassis and the size of the radiator, whether it blocks the memory, and does not support your motherboard platform (most radiators support Intel and AMD multi-platforms). In addition, silicone grease is also very important, try to choose a silicone grease with a thermal conductivity of more than 5. This thing is very cheap, is indeed a very important part of the heat dissipation, evenly coated with a thin layer can be.
