Case Fan Buying Guide: 120 vs 140 mm, PWM and Airflow Explained

Case fans are the cheapest upgrade for a cooler, quieter gaming PC. They bring fresh air to your graphics card and CPU cooler and carry warm air back out. Many cases, however, ship with only one or two fans. In this guide you will learn which size you need, why PWM fans are usually the better choice, when static pressure matters more than airflow, how to connect several fans and what to watch out for with ARGB. At the end you will find five example fans.

Transparency: We have not tested these fans ourselves. Specs come from the manufacturers (ARCTIC, be quiet!, Noctua) and from verified Amazon.de product pages (as of October 2026). We deliberately do not list prices because they change constantly.

The key criteria at a glance

1. Size: 120 or 140 mm?

The usual mounting spots in a case are 120 mm and 140 mm; some specialized cases also take 200 mm fans. According to XPG, larger fans move more air at the same noise level – but real airflow depends on the model, its speed and obstacles such as dust filters. What matters is what your case supports at the front, top and rear. You will find this on the case's product page; our PC case buying guide shows how much the factory fan setup varies.

2. PWM (4-pin) or DC (3-pin)?

A 4-pin PWM fan receives a constant 12 volts and is controlled by a separate signal. Noctua describes it following the Intel specification: a 25 kHz square wave on pin 4. Without that signal the fan runs at full speed. A 3-pin fan, by contrast, is controlled by voltage. be quiet! explains that it usually needs around 5–6 volts to start and therefore cannot spin as slowly as the PWM version. The manufacturer recommends PWM whenever your motherboard supports it – which is the norm on current boards. According to Noctua, a 4-pin plug also fits a 3-pin header as long as there is room next to it.

3. Airflow or static pressure?

Manufacturers list two performance figures:

• Airflow in CFM or m³/h: how much air the fan moves in open space. Important for normal case positions without much resistance.
• Static pressure in mmH₂O: how well the fan pushes air through obstacles. Corsair and be quiet! recommend pressure-focused fans for radiators and dense heatsinks.

be quiet! suggests its high-speed versions for radiators and slower fans for case positions, because very high speeds bring diminishing returns there. XPG adds that dust filters also increase resistance.

4. Reading noise figures

Most manufacturers list noise in dB(A) at full speed. be quiet! says it measures in an anechoic chamber and notes that a quiet apartment sits at around 35–40 dB(A). ARCTIC, on the other hand, lists noise in sone. Because units and methods differ, figures from different brands cannot be compared directly. In daily use, speed matters most anyway – a good fan curve in the BIOS often makes more difference than a few dB(A) on the spec sheet.

5. Bearings and lifespan

The bearing type affects running noise and durability. The examples below use fluid dynamic bearings (ARCTIC, be quiet! Silent Wings 4), a rifle bearing (be quiet! Pure Wings 3) and Noctua's SSO2 bearing. The manufacturers quote very different lifespans: 80,000 hours for the Pure Wings 3, over 150,000 hours (MTTF) for the Noctua and up to 300,000 hours for the Silent Wings 4.

6. Zero RPM mode

Some fans stop completely at a very low PWM signal – ARCTIC lists 0 rpm below 5 % PWM for its P series, Noctua a stop at 0 % PWM. That keeps the PC silent at idle. Check in your fan curve that the fans reliably spin up again under load.

Connecting several fans

A motherboard has a limited number of fan headers. There are three solutions:

• Y-cable: Noctua includes the NA-YC1 with many fans to run two PWM fans from one header.
• Daisy-chaining: ARCTIC's PST fans have an extra 4-pin socket on the cable. ARCTIC recommends no more than five fans per header, because some motherboards only deliver 1.0 A per fan header. Only the first fan in the chain reports its speed.
• Fan hub: For more fans, ARCTIC recommends a hub with its own SATA power.

ARGB and RGB: don't mix them up

Lit fans have a second cable for the LEDs. There are two standards: 5V ARGB (addressable, 3-pin with 5 V, data and ground – as ARCTIC describes it) and 12V RGB. ASUS accordingly distinguishes between "Addressable Gen2" headers for 5 V and "AURA RGB" headers for 12 V on its motherboards. Check your motherboard manual for the header you have and only plug the LED cable into the matching one – according to ASUS with the arrow on the plug aligned to the +5V or +12V pin.

Where do the fans go?

The classic airflow path: intake at the front (and bottom), exhaust at the rear and top. On case pressure, XPG explains:

• Positive pressure: more air in than out. Excess air escapes through gaps, so little unfiltered air is pulled in – which can reduce dust.
• Negative pressure: more air out than in. Air is pulled in through unfiltered openings, often meaning more dust.

XPG's advice for most PCs: slightly positive pressure, for example with one extra intake fan, plus dust filters on every intake. According to XPG, though, temperatures depend more on total airflow and a clear airflow path than on pressure alone.

Five example fans

The following models are well-known case fans available on Amazon.de. They are not test winners but examples of their class. All figures according to the manufacturer or the verified Amazon.de page.

Example model

Value five-pack: ARCTIC P12 PWM PST

Five 120 mm PWM fans in one box – handy if you want to fill a whole case. Each fan has an extra 4-pin socket for daisy-chaining (PST). ARCTIC describes the P12 as pressure-optimized, so it also suits heatsinks and radiators.

Size

120 × 120 × 25 mm

Speed

200–1800 rpm (0 rpm below 5 % PWM)

Airflow

56.3 CFM / 95.7 m³/h

Static pressure

2.20 mmH₂O

Noise

0.3 sone

Bearing

fluid dynamic bearing

Connector

4-pin PWM + 4-pin socket

Warranty

6 years

Right for you if you want several fans at once on a budget and can do without lighting.

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Example model

Budget with high pressure: be quiet! Pure Wings 3 120mm PWM high-speed

Single fan with nine blades and a high top speed. According to be quiet!, its closed-loop motor keeps the target speed even against resistance such as a radiator. be quiet! explicitly lists the high-speed version as a radiator fan.

Size

120 × 120 × 25 mm

Speed

up to 2100 rpm

Airflow

59.6 CFM / 101.2 m³/h

Static pressure

2.41 mmH₂O

Noise

30.9 dB(A)

Bearing

rifle, 80,000 h

Connector

4-pin PWM

Warranty

3 years

Right for you if you want an affordable, pressure-focused fan for a radiator or CPU cooler.

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Example model

140 mm with ARGB: ARCTIC P14 PWM PST A-RGB

140 mm fan with 12 addressable LEDs in the hub. Both the fan cable and the LED cable have an integrated Y-splitter, so you can chain several fans. The LEDs run from the motherboard's 3-pin 5V ARGB header or a controller.

Size

140 × 140 × 27 mm

Speed

200–1900 rpm (0 rpm below 5 % PWM)

Airflow

68.9 CFM / 117.06 m³/h

Static pressure

2.00 mmH₂O

Noise

0.3 sone

Bearing

fluid dynamic bearing

Connector

4-pin PWM + 3-pin 5V ARGB

Warranty

6 years

Right for you if your case has 140 mm mounts and you want to control lighting through your motherboard.

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Example model

Quiet 140 mm for front and radiator: be quiet! Silent Wings 4 140mm PWM high-speed

All-round fan with a 6-pole motor and fluid dynamic bearing. Anti-vibration corners come pre-installed; hard plastic corners for radiators are included. The fan mounts with screws or push pins and supports a zero RPM mode.

Size

140 × 140 × 25 mm

Speed

up to 1900 rpm

Airflow

78.4 CFM / 133.2 m³/h

Static pressure

2.36 mmH₂O

Noise

29.3 dB(A)

Bearing

FDB, up to 300,000 h

Connector

4-pin PWM

Warranty

5 years

Right for you if you want a quiet, high-quality 140 mm fan for the front or a radiator.

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Example model

Premium 120 mm: Noctua NF-A12x25 G2 PWM

The second generation of Noctua's 120 mm flagship, made of Sterrox LCP with a tip clearance of just 0.5 mm between blade tips and frame. Noctua positions it as an all-rounder for cases, heatsinks and radiators. The box includes a low-noise adapter (max. 1500 rpm), a Y-cable, an extension cable, anti-vibration mounts and a gasket for radiators.

Size

120 × 120 × 25 mm

Speed

360–1800 rpm (stops at 0 % PWM)

Airflow

107.3 m³/h

Noise

22.5 dB(A), 18.1 dB(A) with adapter

Bearing

SSO2, MTTF over 150,000 h

Connector

4-pin PWM

Warranty

6 years

Right for you if you want maximum smoothness and are willing to pay considerably more per fan.

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The models compared

Model	Size	Max. speed	Airflow	Noise	Warranty
ARCTIC P12 PWM PST (5-pack)	120 mm	1800 rpm	95.7 m³/h	0.3 sone	6 years
be quiet! Pure Wings 3 high-speed	120 mm	2100 rpm	101.2 m³/h	30.9 dB(A)	3 years
ARCTIC P14 PWM PST A-RGB	140 mm	1900 rpm	117.06 m³/h	0.3 sone	6 years
be quiet! Silent Wings 4 high-speed	140 mm	1900 rpm	133.2 m³/h	29.3 dB(A)	5 years
Noctua NF-A12x25 G2 PWM	120 mm	1800 rpm	107.3 m³/h	22.5 dB(A)	6 years

All figures according to the manufacturer at full speed. Sone and dB(A) are different units and cannot be compared directly.

Pre-purchase checklist

1. Which fan sizes and how many mounts does my case offer?
2. Does my motherboard have enough 4-pin fan headers – or do I need Y-cables, daisy-chain fans or a hub?
3. Is the fan going on a radiator (static pressure) or a free case mount (airflow)?
4. Do I want lighting – and does my motherboard have a 5V ARGB or 12V RGB header?
5. Are the intakes filtered, and am I planning slightly positive pressure?

Frequently asked questions

How many case fans do I need?

For a typical gaming PC, at least one intake fan at the front and one exhaust fan at the rear make sense. With three to five fans, XPG recommends adding one extra intake fan to create slightly positive pressure.

Are 140 mm fans better than 120 mm?

Larger fans can move more air at the same noise level. What matters most, though, is which size your case or radiator accepts.

Can I run PWM fans on a 3-pin header?

Yes, the plug fits according to Noctua if there is room next to the header. Without a PWM signal, however, the fan runs at full speed unless the motherboard controls the voltage.

How many fans can I connect to one header?

That depends on your motherboard. ARCTIC recommends no more than five of its PST fans per header because some boards only deliver 1.0 A per header. Check the value in your motherboard manual.

Do I need high static pressure fans?

Mainly on radiators, CPU coolers and behind dense dust filters. For open positions at the rear or top, a fan with good airflow is usually enough.

Is it worth replacing the pre-installed fans?

Often yes, if the fans are loud, are 3-pin only or your case comes with just one fan. New PWM fans can be controlled more finely.

Sources

As of October 2026. Specs come from the manufacturers and the verified Amazon.de product pages (ASINs in the article text):

• be quiet! – Fan guide (PWM, radiators, noise)
• Noctua – PWM specifications white paper
• Corsair – PC Fans: Static Pressure vs Airflow
• XPG – Case Pressure 101: Intake vs Exhaust
• ARCTIC – P14 PWM PST A-RGB manual (connectors, max. 5 fans per header)
• ASUS Support – 5V and 12V RGB headers (FAQ)
• ARCTIC P12 PWM PST – product page
• be quiet! Pure Wings 3 120mm PWM high-speed – specifications
• be quiet! Silent Wings 4 140mm PWM high-speed – specifications

Manufacturers occasionally change specs and variants. If anything important changes, we will update this article.