S-FLEX 120mm Fan (1200 RPM, SFF21E) Discontinued
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Scythe S-FLEX 120mm Fan (1200 RPM, SFF21E)

Scythe S-FLEX - Premium Quality Quiet Multi-Purpose Cooling Fans

The Scythe S-FLEX fans are equipped with genuine S-FDB (SONY Fluid Dynamic Bearing) manufactured by SONY corporation. S-FDB technology drastically eliminates the friction between the bearing and the shaft which makes this fan nearly inaudible to human ears. Additional suction magnet optimises the magnetic force balance within the rotor to achieve absolute silence. To make this fan even quieter, the fan is equipped with the Linear drive IC for reducing electromagnetic noise.

Conventional ball bearing carries a point contacting structure for the rotation, which gives point supporting situations at dropping impact to damage ball bearing surface which could cause irregular noises. The S-FDB carries a surface contact mechanism for improved anti-shock structure, which is fives times stronger than a conventional ball bearing. Available in three different fan speeds, there is a solution for everybody.

Specifications	S-FLEX 120mm 1200
Fan size (edge to edge)	120 mm
Manufacturer	Scythe
Model	SFF21E
Air volume at full speed (12V), CFM ±10%	49.0
Noise level at full speed (12V), dB(A)	20.1
Fan speed at full speed (12V), RPM ±10%	1200
Power consumption, W	1.20
Weight, g	175
Approximate cable length, cm	30
Life expectancy @ 25°C continuous use	17 years
Power connector	3-pin, 4-pin
Bearing type	S-FDB
Accessories	None
Mounting hardware included	Screws
Fan depth	25 mm
Rated voltage	12 VDC
Warranty	24 months
EAN barcode	4560143268874

Specifications	S-FLEX 120mm 1200
Fan size (edge to edge)	120 mm
Manufacturer	Scythe
Model	SFF21E
Air volume at full speed (12V), CFM ±10%	49.0
Noise level at full speed (12V), dB(A)	20.1
Fan speed at full speed (12V), RPM ±10%	1200
Power consumption, W	1.20
Weight, g	175
Approximate cable length, cm	30
Life expectancy @ 25°C continuous use	17 years
Power connector	3-pin, 4-pin
Bearing type	S-FDB
Accessories	None
Mounting hardware included	Screws
Fan depth	25 mm
Rated voltage	12 VDC
Warranty	24 months
EAN barcode	4560143268874

Product Resources

Scythe website

FAQ

How do I measure fan size?
The size of fan you need will generally be determined by the size of the fan fitting position in your PC case. The sizes of all the fans on our website are shown as measured along any one of the fan’s four sides, NOT the distance between the fan’s screw holes! Our most popular fan size is 120mm, followed by 80mm. This isn’t really dictated by customer preference, but more by recent designs of PC cases.

As for the thickness (depth) of the fan, generally 25mm (1 inch) is by far the most common depth, although smaller fans can have shallower depths such as 15mm or even 10mm. All our fans are 25mm thick unless otherwise stated. If you have any questions about which fan you should order, please don’t hesitate to get in touch.

If you know the distance between the fan mounting screw holes but don’t know what fan size to order, please see the following table. Note that the mounting hole measurements shown below are taken horizontally or vertically between the holes and not diagonally.

Screw hole spacings and fan sizes

Space Between Screw Holes Fan Size

32mm 40mm

40mm 50mm

50mm 60mm

60mm 70mm

72mm 80mm

83mm 92mm

105mm 120mm
I received a small cable (resistor) with my fan; what is it for?
The resistor cable (also called Ultra Low Noise or ULN cable) is designed to allow the fan to run slightly slower for even quieter operation. The benefit in lower running noise is significant. Although the airflow will be reduced slightly, this usually has minimal effect on PC temperature. We would generally recommend using the ULN resistor cable for best results in almost all circumstances.
How can I tell which way the air blows through the fan?
Hold the fan so that the round fan sticker is facing you. You are looking at the rear of the fan. When you plug the fan in, the air will be blowing towards you. If you want a fan to act as an air intake, then the fan sticker will be facing the inside of the case. Some fans also have two small arrows moulded into their plastic housing - one arrow shows the direction of airflow, and the other (at 90°) shows the direction of blade rotation.
Is it possible to use a 4-pin PWM fan or CPU cooler with a motherboard which has only 3-pin fan headers on it?
Electrically, there is no problem doing this - the fourth pin on the fan cable is used purely for PWM control and is not needed in order for the fan to run. So you can plug the 4-pin fan connector onto the 3-pin motherboard fan header, leaving the fourth pin not connected to anything. The fan will potentially run at full speed, so if you would like to reduce the speed of the fan you will need to adjust the fan speed setting in your BIOS or use fan control software such as SpeedFan in Windows.

The only other problem to consider is that occasionally, components immediately adjacent to the motherboard fan header can get in the way of the larger 4-pin fan connector, physically preventing connection. This problem also occurs if you try to use an in-line fan speed controller such as the one made by Gelid.

Another avenue to explore is the possibility of using a bay-mounted fan controller. Several models are available now which provide 4-pin fan headers, so this is an easy way to use 4-pin PWM fans in a PC system which has only 3-pin fan headers on its motherboards. When using this method, you may find it necessary to disable any fan warning settings in your motherboard BIOS, since the motherboard may incorrectly believe that its CPU fan has failed when the fan is connected to a fan controller rather than directly to the motherboard itself.