120mm Fans vs. 140mm Fans: PC Fan Sizes Explained

Introduction

New PC builders often overlook PC case fans. Most of them consider them as an aesthetic afterthought. However, peak PC performance is reliant on picking the right PC fan. The quality of the fan impacts PC noise levels, parts longevity, and gaming hardware performance. It also lowers the chances of thermal throttling and impacts power consumption.

When you have finally decided to buy a PC case fan, the first thing to consider is the size. There are sizes that range from 80mm to 200mm. However, two sizes, 120mm and 140mm, dominate PC cases for compatibility. While you can install both sizes in most PC cases, selecting the right one can actually impact your hardware energy efficiency and overall cooling performance. This article will put both sizes to the test. Where the real-world impact on PC hardware will be fully analyzed.

Head-to-Head: 120mm vs. 140mm Fans

Airflow and Cooling Efficiency

When comparing two major sizes, the first difference is the amount of space they take and the airflow it provides. When it comes to airflow, the 140mm fan has a major advantage. The surface area is 36% bigger than 120mm. It means that the bigger fan will push more volume of air for the same revolutions.

The flow of air is the key parameter in PC fans. The 140mm can push up to 97 CFM, while a 120mm provides a maximum of 74 CFM. Since they are bigger, they spread out the air more efficiently. It means that the cool air will reach more components like RAM and VRM modules. In case you need focused airflow, then 120mm offers better performance. Builders can mount the 120mm fan directly in front of the M.2 NVMe SSD to keep it cool and prevent thermal throttling. Or they can focus on the graphics card.

In real-world testing results three 140mm fans pull air more effectively. Under maximum load with a high-end GPU and CPU, the system often runs at a stable 78 C. These are results obtained at average temperature and humidity conditions.

Airflow and Size Comparison Table

Noise Levels and Acoustics

The bigger fans require lower RPM to push the same amount of air in comparison to the small fan. The result is a much quieter computer. If we analyze the source of noise, we can see that the blades are slicing air at a specific rate. A higher rate means more high-pitched whining sound. Rather than listening to the rough, noisy 120mm fans, most users prefer the humming noise of a bigger fan.

When using premium engineering design, the blades of the 120mm may perform better in comparison to substandard fans. The turbulence that creates the noise is reduced, which lowers the drone-like noise for small fans. A high-quality 120mm fan rotating at  1100 RPM will have around 17.2 dBA. In comparison, a 140mm sub-standard fan running at a slower 950 RPM will measure 28.5 dBA.

The key difference would be the use of silicon shock pads and dampening features. They stop the whole PC case from contributing to the rattling noise. Modern fans that come with a 4-pin connector allow precise control of speed with PWM. It allows speed control based on the requirement to reduce noise levels.

Static Pressure and Resistance

One of the biggest influencers of noise level is the static pressure. It's the ability of the fan to create a pressure difference to start flow across all the obstacles that come within a PC case. The measuring unit is mm-H2O. Smaller fans have higher static pressure in comparison to larger fans.

• 120mm Fan: 4.38mm-H2O
• 140mm Fan: 3.79mm-H2O

A higher static pressure means that the fan will push more volume of air while requiring lower RPM operation. The 120mm fans are therefore chosen for cooling tasks that require force. These are particularly useful in flowing air across a dense liquid cooling radiator for AIO units. It can pass more air while operating at lower RPM. For example, a 360mm AIO unit can actually perform better, lowering the CPU cooler by 4 C lower than 140mm alternatives for the same noise levels.

Technical Factors Influencing Performance

RPM and Rotational Dynamics

The smaller 120mm fan is designed to provide high RPM. They typically have an RPM range of 1200 to 2000 revolutions per minute (RPM). In comparison, the 140mm has 600 starting RPM, which goes up to 1200 RPM when running at max speed. Larger fans tend to have a higher centrifugal force, as the 140mm fans have dimensions that stretch away from the center. The result is high stress on the material. Therefore, engineers run them at lower RPM to ensure dynamic stability.

Smaller 120mm fans have a higher static pressure gradient. It allows them to force air into the PC case. The pressurized air tries to escape from small gaps where filters are not present. Since the air is flowing outwards from small gaps, the chances of dust coming inside the case become nil. Moreover, modern PWM-based fans adjust their speed based on temperature sensors. They reduce their RPM once everything cools down.

Bearing Technology and Longevity

One of the most valuable components in any PC fan is the bearing. It directly determines the life of the fan. Here are some key features you should consider:

• Oil-Based Fans: Fans that work with a liquid-based bearing mechanism, popularly known as Hydraulic and Fluid Dynamic Bearing, are considered premium. They have a microscopic layer of oil between moving parts.
• Reduce Resistance: The key is to design a bearing that has minimum internal resistance. The shaft of the fan and motor needs to be supported without hindering its rotational forces.
• Lifespan: Owing to the exceptional performance of FDB. They can last more than 30,000 to 40,000 hours without failure.
• Choice of Material: Premium fans often come with copper alloy shafts and heat-dissipating steel plates. The cooler operation extends the life of the fan motor by 10 years.
• Maglev Bearings: The absolute peak of engineering is magnetic drive and “Maglev” bearings. They use magnetic forces to keep the shaft suspended inside the hub. It completely eliminates any friction. These are premium-grade niche fans.

Note: Fans bearing life depends on the operation temperature, which is impacted by the environmental temperature.

Power Consumption and Efficiency

Most users consider the power consumption for fan units as insignificant. However, when you have a large PC case such as a full tower, you may need to consider its power. Large fan blades are heavy, which means they need more power. These consume in the range of 3.6W in comparison to the 1.8W by a 120mm fan. However, we cannot compare the efficiency based on the power consumption alone.

For computers, 140mm fans actually provide better energy efficiency in comparison to 120mm. As they have push larger volume of air per unit power consumed. The 140mm fans boast 18% efficiency. Modern fans come with daisy-chaining capability, which allows fans to connect together using one cable. It simplifies the build significantly.

Conclusion

If you are still skeptical about the fan size, let's break down the complete discussion into precise bullet points. It will assist in quick and clear decision-making.

• Choose 120mm if you want a high static pressure and a positive pressure enclosure. They are great for radiators and densely packed PC cases with cables.
• Go for 140mm if you want low noise performance and own a high-air flow PC case.

Whether you pick 120mm or 140mm its vital to find a product that is capable of providing the long-term operation and premium aesthetics. For this consider, ESGAMING products. Their Prism Pro ARGB and Silent Flow series offer the premium performance and aesthetics required by performance rigs.

Founded in 2020, ESGAMING is an innovative hardware brand dedicated to Gen Z gamers and esports culture. We make your dream setup look and run better with our fishtank PC cases, efficient power supplies, and premium cooling setups. Designed for the next generation, ESGAMING empowers young PC builders worldwide to level up their desktop vibe without limits.

For more information, visit www.esgamingpc.com