Noctua NF-S12B FLX Fan

(4.5 star rating) Written by: William Ford

Today we're going to take a look at two Noctua case fans that look identical but are designed slightly different for different computer operating requirements. The first fan we tested is the Noctua NF-S12B ULN. This fan runs at two different speeds; 700 RPM or 500 RPM. The main feature of this particular fan is that it is designed to run as quietly as possible and still cool effectively. The fan we will look at now is the Noctua NF-S12B FLX which runs at three speed modes of 1200 RPM, 900 RPM and 600 RPM for flexible cooling needs.

Design

This fan fits 120mm fan mounts and comes with four screws but also optional rubber grommets to use instead of screws for ultimate silent running. The fan frame is beige and the blades are brown and the power cables are plenty long enough to reach the power jumpers on just about any motherboard. The fan sports Noctua's well proven SSO-Bearing for supreme quiet operation and stability. The blade tips are also beveled with extended leading edges for 10% more airflow than previous models. This fan also sports Noctua's SCD2 technology (Smooth Commutation Drive 2) that eliminates torque variations and switching noises. Sound familiar? That's because it is exactly like the NF-S12B ULN except for the speed differences.

Box Contents

• 1 - NF-S12B FLX 120mm Fan
• 1 - Molex power adapter
• 1 - ULN adapter
• 1 - LN adapter
• 4 - Rubber mounting grommets
• 4 - Mounting screws

Specifications

• RPM: 1200 / 900 / 600
• Airflow: 100.6 m³/h / 75.8 m³/h / 49.2 m³/h
• Acoustical noise: 18.1 dB(A) / 10.6 dB(A) / 6.2 dB(A)
• Input Power: 1.2 W
• Operating Voltage: 0.10 A
• MTBF: > 150,000 h

Features

• Highly optimised impeller with Bevelled Blade Tips
• 2 speed settings for maximum quietness
• Smooth Commutation Drive 2
• SSO-Bearing

Installation

The installation is done the same as the ULN version. You find a place in your computer case to mount a 120mm fan and then either screw the fan into place using the four mounting screws or you can use the rubber mounting grommets to help keep vibration down. The grommets simply insert from the outside of the case and through one side of the fan, holding it securely in place. Installation takes about two minutes for even the most technically challenged. Once the fan is installed you can attach it directly to the motherboard using the attached 3-pin plug or if you do not have a place on the motherboard to attach the fan you can use the Molex adapter to get power directly from the power supply.

You also have a choice of using the ULN (Ultra-low noise) adapter or the LN (low noise) adapter. Using the ULN will slow the fan speed down from 1200 RPM to 600 RPM; the LN adapter will slow the fan to 900 RPM. The fan is very quiet at 1200 RPM and almost inaudible at 900 RPM. When the fan is running at 600 RPM it cannot be heard over the CPU cooler or the GPU cooler.

NF-S12B FLX Box		Box Contents

Performance

After installing the fan in a typical mid-tower PC case we ran the fan for two hours under each setting then checked the revolutions per minute and checked the ambient temperature inside the case. The NF-S12B FLX fan was installed into the same PC that we used to test the NF-S12B ULN. The FLX version replaced the ULN for our testing purposes.

Test Setup

• Operating System: Vista Home Premium x64
• Motherboard: ECS G45-MT2
• CPU: Intel Core 2 Quad E6600 @ 2.40GHz
• Memory: 4GB G-Skill DDR2 6400
• CPU Heatsink: Noctua NH-C12P
• Video card: EVGA GeForce 8800 GT 512MB
• Hard drive: Hitachi 500GB SATA
• Case: Antec SOLO

This time we only left the computer idle for an hour between checking the RPM and ambient temperature inside the case. The computer was left to idle with the ULN adapter attached for one hour and the readout showed 601 RPM and the ambient temperature inside the case was 36° Celsius. This is an acceptable temperature and the speed was spot-on. Next we tested the fan with the LN adapter for one hour. The readout showed 898 RPM and the ambient temperature was 32° Celsius. Last we left the PC run idle for another hour with no adapter and the readout showed 1200 RPM right on the money with an ambient case temperature of 31° Celsius. These were the results with the PC running idle.

Next we tested each setting for 20 minutes with the PC under load. To stress the computer and generate heat we ran NVIDIA's Adrianne (a 3D graphic demo) as well as run a virus scan to maximize the heat generated.

So you can see that the ambient temperature reaches a threshold with the fan at 1200 RPM where it doesn't seem to make any difference if the PC is idle or under load. All of the temperatures are acceptable and the fan is extremely quiet at all settings. This fan is capable of keeping a powerful computer cool and quiet at the same time. It can also handle demanding cooling jobs for high performance computers like gaming machines and servers.

Closeup view of blades		Overhead view

Noctua NF-S12B FLX 120mm Fan

The NF-S12B FLX is a great fan for high power computers and can be slowed by using an adapter on the power plug to slow the fan down for quieter uses. Both the NF-S12B FLX and the NF-S12B ULN are very nice fans - but if you need the cooling power you will want the FLX version. If silence is you main concern you would want the ULN version.

Comparing the two side by side, I would prefer the FLX version for its variable speed and its flexibility to work in most all situations. The only drawback to both of these models is that you have to open the computer and attach an adapter to change the fan speeds. It would be nicer to have a built in resistor in the fan with a switch that can be accessed from the back of the PC instead of having to switch adapters every time you want to change the speed; but then again, that's why we have fan controller panels.

Pros: Its quiet, cools effectively and is three speed adjustable.

Cons: As with the ULN version, it's pricier than other fans. It would be nicer to have a built in resistor in the fan with a switch that can be accessed from the back of the PC instead of having to switch adapters every time you want to change the speed.

Rating: 4.5 out of 5

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