PC Cooling: A Guide to Case Fans

Efficient cooling is a critical factor in ensuring optimal performance and longevity of PC components. Case fans play a vital role in maintaining a stable internal temperature by actively circulating air and dissipating heat.

In this comprehensive guide, we will delve into the intricacies of case fan selection, placement, and configuration to help you achieve the best possible cooling solution for your PC build.

Fundamentals of PC Cooling

Understanding Heat Generation in PC

The primary sources of heat within a PC include:

• Central Processing Unit (CPU)
• Graphics Processing Unit (GPU)
• Power Supply Unit (PSU)
• Hard drives and solid-state drives
• Motherboard components, such as VRMs and chipsets

When these components are subjected to heavy workloads, such as resource-intensive gaming or advanced tasks like video rendering, the amount of heat generated increases substantially.

The Role of Airflow in Cooling

Effective cooling in a PC relies on the fundamental principle of airflow. By actively moving air through your computer case, you can continually introduce cooler ambient air while expelling warmer air, thus regulating internal temperatures. This process of air intake and exhaust is facilitated by strategically placed case fans.

Key aspects of airflow in PC cooling include:

• Air intake: Cool air is drawn into the PC case through intake fans, typically located at the front or bottom of the case. This fresh air helps to lower the temperature of internal components.
• Air exhaust: Warm air that has absorbed heat from components is expelled from the case through exhaust fans, usually positioned at the rear or top of the case.
• Airflow direction: Maintaining a consistent direction of airflow, from front to back and bottom to top, helps optimize cooling efficiency by reducing turbulence and ensuring a steady stream of cool air passes over heat-generating components.
• Airflow balance: Achieving a balance between air intake and exhaust is crucial to maintain optimal air pressure within the case. This balance helps prevent issues like dust buildup or inefficient cooling.

In addition to case fans, other cooling solutions such as CPU coolers and GPU coolers also rely on airflow to dissipate heat. These components often feature heatsinks with fins that increase surface area, allowing air to pass through and carry heat away more effectively.

Types of Case Fans

Standard Fans Vs. High Static Pressure Fans

Standard case fans, also known as airflow fans, are designed to move large volumes of air through a PC case with minimal resistance. These fans typically have a lower number of blades with a more open design, allowing for optimal airflow and efficient cooling of internal components. Standard fans are ideal for cases with unobstructed airflow paths and are commonly used as intake or exhaust fans.

High static pressure fans are engineered to overcome resistance caused by obstacles such as radiators, heat sinks, or densely packed case layouts. These fans feature a higher number of blades with a more closed design, enabling them to push air through restricted spaces more effectively. High static pressure fans are best suited for use with CPU coolers, radiators, or in cases with limited airflow due to their ability to maintain adequate cooling even in challenging scenarios.

RGB vs. Non-RGB Fans

RGB fans feature built-in LED lighting that can be customized to display various colors and effects, adding a visually appealing element to your PC build. These fans are popular among enthusiasts who value the aesthetic qualities of their systems and enjoy showcasing their rigs.

However, it’s essential to note that RGB fans may come with a slight performance trade-off compared to their non-RGB counterparts. The additional electronics required for the lighting effects can potentially impact the fan’s overall efficiency and noise levels. Some RGB fans may have slightly lower airflow or higher noise output compared to similar non-RGB models.

Non-RGB fans prioritize performance over aesthetics. These fans are designed solely for the purpose of providing optimal cooling, without the added complexity of LED lighting. As a result, non-RGB fans often have better airflow and static pressure ratings, as well as lower noise levels, making them ideal for users who prioritize cooling performance above all else.

Types of Fan Specifications

• 40 mm Case Fan: These compact fans are ideal for small form factor (SFF) cases or tight spaces where larger fans won’t fit. While they have limited airflow capacity compared to larger sizes, they can provide targeted cooling for specific components.
• 60 mm Case Fan: Slightly larger than 40 mm fans, 60 mm fans are still compact and suitable for SFF cases. They offer improved airflow rates and can be used for spot cooling or as supplementary fans in larger cases.
• 80 mm Case Fan: 80 mm fans strike a balance between size and performance. They generate decent cooling while maintaining a relatively small footprint. These fans are commonly used in micro-ATX and mini-ITX cases or as additional intake or exhaust fans in larger cases.
• 92 mm Case Fan: 92 mm fans provide a step up in airflow capacity compared to 80 mm fans. They are versatile and can be used in a variety of case sizes. Many CPU coolers also utilize 92 mm fans for efficient heat dissipation.
• 120 mm Case Fan: 120 mm fans are the most popular and widely used size in modern PC cases. They offer excellent airflow rates and static pressure, making them suitable for both intake and exhaust positions. Multiple 120 mm fans can be used to create an optimal airflow configuration.
• 140 mm Case Fan: 140 mm fans are larger and can move more air than 120 mm fans while maintaining lower noise levels. They are often used in high-end cases or as front intake fans to maximize cool air drawn into the case. Some CPU coolers and radiators also support 140 mm fans for improved thermal performance.
• 200 mm Case Fan: 200 mm fans are the largest commonly available size. They are designed for cases with ample space and can move significant amounts of air at low rotational speeds, resulting in quiet operation. However, due to their size, compatibility with cases and other components may be limited.

Types of Bearing

The bearing type of a case fan can significantly impact its performance, longevity, and noise levels. Here are the three main types of bearings found in PC case fans:

• Rifle Bearings: Also known as sleeve bearings, rifle bearings are the most common and affordable type. They consist of a metal shaft that rotates within a sleeve lubricated with oil. Rifle bearings are suitable for basic computing tasks and offer decent cooling performance at lower speeds. However, they may have a shorter lifespan and can be prone to bearing issues if mounted horizontally or operated at higher temperatures.
• Ball Bearings: Ball bearings offer improved durability and performance compared to rifle bearings. They feature metal balls that reduce friction between the bearing shaft and the fan housing, allowing for smoother rotation and less noise. Ball bearings can handle higher rotational speeds and are suitable for more demanding cooling scenarios, such as gaming PCs or systems with overclocked components. They also have a longer lifespan and are more resistant to dust build-up.
• Maglev Bearings: Maglev (magnetic levitation) bearings are a newer and more advanced technology in PC case fans. They use magnetic forces to suspend the fan blades, eliminating physical contact and friction. This results in nearly silent operation, increased durability, and improved cooling efficiency. Maglev bearings can maintain optimal performance over extended periods and are ideal for users seeking the best balance between cooling performance and noise levels. However, they come at a higher price point compared to other bearing types.

Types of Case Fan Header Connections

Case fans connect to the motherboard or fan controllers using either 3-pin or 4-pin connectors.

• 3-pin Connectors: 3-pin fan connectors, also known as DC (direct current) connectors, have been the standard for many years. They feature three pins: ground, power (usually 12V), and tachometer (for monitoring fan speed). 3-pin fans run at a constant voltage and speed, which can be adjusted using fan controllers or by connecting them to adjustable fan headers on the motherboard. However, 3-pin fans do not support pulse width modulation (PWM) for more advanced speed control.
• 4-pin Connectors: 4-pin fan connectors, also known as PWM connectors, are the more modern and versatile option. They have an additional fourth pin that carries a PWM signal. This signal allows the motherboard or fan controller to dynamically adjust the fan speed based on temperature readings from various sensors. 4-pin fans can run at lower speeds when cooling demands are low, reducing noise levels and power consumption.

Intake vs. Exhaust Fans

Intake fans draw cool air from outside the PC case into the interior, providing fresh air to the internal components. These fans are typically mounted on the front or bottom of the case, directing airflow towards the heat-generating components like the CPU, GPU, and motherboard.

Exhaust fans expel warm air from inside the case to the exterior. They are usually positioned on the rear or top of the case, allowing the accumulated heat to escape and preventing the buildup of hot air within the system.

How to Identify Fan Orientation

Most fans have arrows embossed on their frame or blades, indicating the direction of airflow. The air flows from the side with the fan’s open frame towards the side with the fan’s support struts or grille.

Another way to determine fan orientation is by examining the fan’s power cable. In most cases, the side with the power cable is the exhaust side, while the opposite side is the intake.

Positive vs. Negative Air Pressure

The balance between intake and exhaust fans determines the air pressure within your PC case. There are three main configurations:

1. Positive air pressure: This setup occurs when the total airflow from intake fans exceeds that of exhaust fans. As a result, more air is forced into the case than expelled, creating a slight overpressure. Positive pressure helps minimize dust buildup, as the excess air pushes out through the case’s crevices, preventing dust from entering. However, this configuration may lead to slightly higher temperatures due to the reduced exhaust flow.
2. Negative air pressure: In this configuration, the total airflow from exhaust fans surpasses that of intake fans. This creates a slight vacuum inside the case, drawing air in through any available openings. While negative pressure can improve overall cooling performance, it also increases the risk of dust accumulation, as the unfiltered air is sucked into the case.
3. Neutral air pressure: A balanced cooling setup is achieved when the total airflow of intake and exhaust fans is equal. This equilibrium maintains a stable internal environment, balancing temperature and dust management. Neutral pressure is generally recommended for optimal performance with minimal noise levels.

Common Fan Placement Strategies

• Blue: CPU Cooling
• Green: Motherboard
• Yellow: Graphics card
• Red: Power supply

Air cooling

In most cases, only 3 intakes are needed and 1 exhaust is needed. Even when the air duct is regular, the fan performance of the radiator body is not that important. Positive pressure difference (intake volume is greater than exhaust volume) will naturally pump heat out of the chassis.

If you find heat accumulation at the upper back of the chassis, you should increase the speed of the exhaust fan at the rear, or use an exhaust fan with a larger air volume, instead of adding a fan on the top.

Water cooling

This is how water cooling is used in most chassis.

In fact, there is no essential difference from the air cooling solution above, except that the addition of the exhaust fan will change the pressure difference of the chassis, and it may be necessary to increase the speed of the front intake fan to ensure the positive pressure difference. And compared with air cooling, this configuration does not pay much attention to the airflow shape of the intake fan.

The disadvantage of this structure is that the radiator will more or less consume the waste heat of the graphics card, so the air volume requirement for the intake fan will be higher, otherwise during continuous operation, the replenishment speed of fresh cold air cannot keep up with the speed at which the graphics card heats the air in the chassis.

Under this structure, the exhaust fan at the rear of the chassis is no longer important, but is only used to guide the airflow direction and assist in exhausting the waste heat of the graphics card.

Water-cooled front

Some particularly compact tower chassis and machines with a large CPU load may need to use this layout. It should be noted that under the front radiator working condition, the fan should be unconditionally given priority to blowing rather than sucking. The radiator fan should be installed between the radiator and the fan rack to blow the external cold air to the radiator and fill it into the chassis.

In this layout, the radiator fan takes on the tasks of both intake and exhaust, and the performance requirements of the fan are very high. It may be necessary to use a high-speed fan as appropriate.

How to Choose PC Cooling Fans

When selecting case fans for your PC, consider the following factors to ensure optimal performance and compatibility:

1. Size: Fans come in various sizes, with common options being 120mm and 140mm. Choose a size that fits your case’s fan mounts and allows for adequate air movement.
2. Static Pressure vs. Airflow: Depending on your cooling needs, you may prefer fans optimized for high static pressure (ideal for radiators and heat sinks) or those designed for maximum airflow (best for unobstructed intake and exhaust).
3. Noise Level: Consider the noise output of the fans, especially if you prioritize a quiet computing environment. Look for fans with low decibel ratings or those designed for silent operation.
4. Bearing Type: The type of bearing used in a fan affects its lifespan, noise level, and overall performance. Common options include sleeve, ball, and fluid dynamic bearings, each with their own pros and cons.
5. RPM and CFM: A fan’s rotations per minute (RPM) and cubic feet per minute (CFM) ratings indicate its speed and airflow volume, respectively. Higher values generally mean better cooling but may also result in more noise.
6. Aesthetics: If you have a case with a transparent side panel, you may want to consider fans with LED lighting or a specific color scheme to enhance the visual appeal of your build.
7. Compatibility: Ensure that the fans you choose are compatible with your motherboard’s fan headers (3-pin or 4-pin) and your case’s mounting options.