Scythe GlideStream, Slip Stream XT, and Grand Flex Fans

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Scythe Grand Flex

Specifications: Scythe Grand Flex
Manufacturer Scythe Power Rating 2.4 / 5.4 W
Model Number SM1225GF12M / SM1225GF12SH-P Airflow Rating 61.1 / 96.8 CFM
Bearing Type Sealed Precision FDB Speed Rating 1600 / 2400 RPM
Frame Size 120 x 120 x 25 Noise Rating 28.5 / 39.5 dBA
Hub Size 48 mm Header Type 3-pin / 4-pin with molex adapter
Blade Diameter 112 mm Fan Mounts Screws, Isolators
Cable Length 50 cm Weight 170 g
Starting Voltage 3.0~3.5 / 5.5~6.0 V Number of Samples 2
Corner Type Open Retail Availability Yes
Extras: 20 cm molex adapter with 30 cm 3-pin RPM sensor cable, rubber isolators

The Grand Flex is easily the most interesting addition to Scythe's lineup. It uses fluid bearings rather than sleeve, which Scythe claims has greater longevity and produces less noise (which begs the question why they aren't used in all their fans). The large 48 mm hub and truly unusual blade design makes it seem like a follow-up to the Gentle Typhoon.

Available in just the 120 mm size, you can choose between 800, 1200, 1600, 2000, and 2400 (PWM) RPM models. Our sub-2000 RPM samples all sounded surprisingly similar when running at the same speeds but the PWM model had a clickiness at lower speeds that was completely absent in the 3-pin varieties. We decided to test both the 1600 and 2400 (PWM) RPM variants.

The Grand Flex appears to have the least amount of quality control issues. One of the 800 RPM "SL" had a dryer hum than the other and there was a minor pitch difference in the 2400 RPM PWM model but these minor inconsistencies were the only ones we could detect in the whole lot.


The fan is embedded in a traditional square casing with some modifications to the center of each side. Like the Slip Stream 140XT, ridges are present but they are shallower and a lip has been cut into the frame as well.

Near the motor, a piece of each blade has been cut and raised. This seems counterintuitive as they resemble the flaps on aircraft which are designed to create drag to slow it down for landings. There are also a couple of spikes on the struts above pointing toward them.

A head on shot of the Grand Flex. Each fan blade more closely resemble an axe than a wing.

This is the screen capture of Fan Xpert 2's auto-analysis of the Scythe Grand Flex "M".

This is the screen capture of Fan Xpert 2's auto-analysis of the Scythe Grand Flex "SH-P".

If you're hoping to run at very low speeds, the 3-pin version of the Grand Flex has a definitive edge. It's capable of spinning up at about 350 RPM while the PWM model bottoms out at approximately 600 RPM.


Acoustic analysis of the Scythe Grand Flex "M".

Acoustic analysis of the Scythe Grand Flex "SH-P".

At top speed, the PWM model puts out so much air that it's difficult to ascertain its acoustics properties. At 1500 RPM, both fans are turbulent and buzzy and the 3-pin version sounds somewhat scratchy. At 1100 RPM, they fans begin to hum but the PWM model develops a more complex character. Its buzzing is less annoying but also begins to click at close proximity. At lower speeds, the 3-pin model mainly hums with the intensity dissipating with the speed, while the 4-pin model continues to click.

SPCR Test Results: Scythe Grand Flex-M
Fan Speed (RPM)
1500
1100
900
700
550
SPL (dBA@1m)
27~28
19~20
15
12
11~12
Thermal Rise (°C)
19
23
26
30
36
Airflow in/out (FPM)
490/370
350/290
-
-
180/150
SPCR Test Results: Scythe Grand Flex-SH-P
Fan Speed (RPM)
2500
1500
1100
900
700
SPL (dBA@1m)
40
27
18
14
12
Thermal Rise (°C)
14
18
21
25
31
Airflow in/out (FPM)
770/670
-
340/290
-
-

The Grand Flex is the only fan that exhibited any appreciable difference between the 3-pin and 4-pin models when it came to performance and measured noise. The PWM version was slightly ahead in both regards at 1500, 1100, and 900 RPM.

Its extremely unusual design also apparently gave it a unique property. This is the only fan we've ever tested with a higher input than output airflow.



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