120 mm vs 140 mm Fans: Performance and Size Considerations

When building or upgrading a computer, choosing the right fan size for your case is an essential factor for maintaining optimal temperatures and system stability. We often come across two popular fan sizes—the 120mm and the 140mm. Both sizes have their unique advantages, and our choice can influence not only the cooling performance but also the acoustics and compatibility within our PC build.

Two computer fans, one 120mm and one 140mm, placed side by side on a flat surface. The larger fan is visibly bigger than the smaller one

The 120mm fans are widely used due to their universal fit in most computer cases and cooling systems. They are a trusted option for good airflow and are often more affordable, making them a practical choice for those of us on a budget. On the other hand, the 140mm fans are known to move more air at lower rotations per minute (RPM), offering quieter operation and potentially better cooling capacity, which is particularly beneficial for high-end or overclocked systems.

Choosing between these fan sizes depends on several factors, including the size of our case, the components we need to cool, and whether we prioritize lower noise levels over cost. We’ll look at compatibility, performance, and noise level trade-offs to help make an educated decision that best suits our computer’s cooling needs.

Understanding Fan Size and Its Relevance

When choosing a cooling fan for your PC, size matters. Fan size directly affects compatibility, cooling efficiency, and noise level.

Comparing Dimensions: 120mm vs. 140mm

  • 120mm Dimensions: Typically, these fans measure 120mm x 120mm x 25mm.
  • 140mm Dimensions: A common size for 140mm fans is 140mm x 140mm x 25mm.

The difference in sizes may seem minor, but it plays a significant role when fitting them into different PC cases. The extra 20mm on each side for the 140mm fans can lead to a snugger fit or may not fit at all in compact cases.

Impact on PC Builds: Compatibility and Fit

When building a PC, especially smaller form factors like Mini ITX, fan size can become a critical consideration. Not all cases can accommodate larger fans.

  • Mini ITX Compatibility: Usually favors 120mm fans due to their smaller footprint.
  • PC Cases: Larger mid or full-tower cases tend to support both 120mm and 140mm fans.

This compatibility must be checked against the case specifications to ensure a proper fit without modifications.

Fan Size and Cooling Performance

Cooling performance is correlated with fan size. Compared to 120mm fans, 140mm fans often offer higher airflow and can run quieter due to slower rotational speeds.

  • 120mm Fans: Generally provide sufficient cooling with a slight compromise on noise.
  • 140mm Fans: Due to their larger size, they can move more air, often resulting in better cooling and lower noise levels. They are mentioned to have higher airflow and can offer slightly more static pressure.

Our goal is to match our cooling needs to the fan size without overlooking the importance of our case’s limitations and preferences for noise level and aesthetics.

Performance Parameters of Fans

A comparison of 120 mm and 140 mm fans in a test environment with airflow and noise level measurements

When we evaluate cooling solutions for our builds, it’s essential to consider the performance parameters that affect the overall efficiency of the fans.

Airflow and Static Pressure Efficiency

Airflow: Measured in cubic feet per minute (CFM), airflow is a crucial factor; it determines how much air a fan can move through your system. Generally, 140mm fans offer a higher CFM due to their larger size, translating to better cooling potential under optimal conditions.

Static Pressure: This is the fan’s ability to push air through obstructions like heatsinks or radiator fins. A fan with high static pressure performs more effectively in restrictive environments.


  • 120mm Fan: 62 CFM at 1.0mm H₂O
  • 140mm Fan: 90 CFM at 1.8mm H₂O

Noise Levels: What to Expect

The Noise Level of a fan is typically measured in decibels (dB). Larger fans usually operate quieter at lower RPMs while maintaining similar airflow to their smaller counterparts.

Expectations for Noise Levels:

  • 120mm Fans: Hover around 18-30 dB
  • 140mm Fans: Often stay below 20 dB when under normal loads

RPM: The Speed Factor

RPM stands for revolutions per minute, and it indicates the speed at which the fan blades spin. Generally, a higher RPM means more noise but can also signify increased airflow and cooling capacity.

Speed Comparisons:

  • 120mm Fan: Around 2000 RPM
  • 140mm Fan: Near 1200 RPM

It’s important for us to remember that while RPM can give a glimpse of performance, it’s not the sole determinant of a fan’s cooling efficiency. The actual performance may vary depending on the balance of airflow, static pressure, and the specific cooling requirements of the system.

Design Considerations and Additional Features

A computer case with options for 120 mm and 140 mm fans, highlighting airflow and size differences

When selecting a fan for your PC, considering design aspects such as bearing types, airflow influence, and additional features like lighting is essential to ensure longevity and performance.

Bearing Types and Lifespan

Bearing type is crucial for the durability and operation of fans. We often see that the most common types include:

  • Sleeve Bearings: Cheaper but with a shorter lifespan, typically quieter at the start but may get noisier over time.
  • Ball Bearings: More durable with a longer lifespan; they tolerate higher temperatures and are more reliable overall.
  • Fluid (Hydro) Dynamic and Magnetic Bearings: These offer the longest lifespan and the most silent operation, ideal for heavy use systems.

The bearing chosen directly impacts the lifespan of the fan. Generally, better bearings mean a longer life for your fan.

Influence of Design on Airflow

The blade design of a fan significantly affects its airflow and efficiency. For example, a fan with a higher blade count but shorter blades might not move as much air as a fan with fewer but longer blades. The curvature and angle of blades also play a part. We recommend ensuring that design complements your system’s cooling needs.

Lighting and Aesthetics

RGB lighting has become increasingly popular for personalizing the look of a build. Not all fans offer this feature, so if aesthetics are important for your build, selecting fans with built-in lighting might be beneficial. These fans often come with software that allows us to change the color and lighting effects.

While lighting does not affect fan performance, it contributes to the overall visual appeal of your system. Remember, additional features like lighting can lead to a higher price point.

Cost-Benefit Analysis

In evaluating the cost versus benefit of 120 mm versus 140 mm fans, it’s crucial to consider not only the initial price point but also the value for money, brand reputation for quality, and long-term investment potential.

Price Comparison and Value for Money

When comparing 120 mm and 140 mm fans, the cost difference can be significant, with 140 mm fans typically costing more due to their larger size and the additional materials used in their construction. However, the value for money isn’t just about the sticker price. A 140 mm fan often provides better airflow and can operate at lower noise levels, which might justify the extra expense for users placing a premium on a quiet and cool system. In contrast, 120 mm fans often win out in price-sensitive situations where budget constraints are tight, offering good performance at a lower cost.

Quality and Brand Reputation: Noctua Case Study

Noctua is reputed for producing high-quality fans that exemplify durability and exceptional performance. Take the Noctua NF-A12x25 as an example of a 120 mm fan with superb build quality that ensures long-term performance. Similarly, their 140 mm models, such as the Noctua NF-A14, continue this tradition, often surpassing 120 mm models in terms of airflow and noise optimization. The reputation of Noctua fans suggests that while the upfront cost may be higher, the quality of these fans can provide better long-term value.

Assessing the Long-Term Investment

We look at fans not just as cooling solutions but as investments in our system’s health and longevity. In assessing long-term cost benefits, 140 mm fans tend to have a lower RPM while moving a comparable volume of air, which can lead to less wear over time and extended lifespan, potentially meaning fewer replacements and better performance stability. On the other hand, if a 120 mm fan suits our system’s requirements and is from a reputable brand, it could also be a wise investment, especially when budget is the limiting factor.

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