Fan Roundup #5: Attack of the 120 Scythes

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SCYTHE DFS122512L-PWM

Ambient noise at the time of testing was 18 dBA. This ambient level was the same for every test conducted for this review.

Brand Scythe Power Rating 0.16A
Manufacturer Scythe Airflow Rating 12.38 ~ 52.71CFM
Model Number DFS122512L-PWM
RPM Rating 310(±200) ~
1200rpm(±10%)
Retail Availability Yes Noise Rating Immeasurable ~ 24.89 dBA
Bearing Type Sleeve Header Type 4-pin PWM
Hub Size 1.58" Starting Voltage 7.2
Frame Size 120 x 120 x 25 mm Number of Samples 1
Weight 140g Variance Noted N/A
Voltage
Noise
RPM
CFM
12V
23 dBA@1m
1180 RPM
33 CFM
9V
19 dBA@1m
850 RPM
21 CFM
@700 RPM (8.1V)
~18 dBA@1m
700 RPM
18 CFM
@500 RPM (7.6V)
<18 dBA@1m
500 RPM
11 CFM
@20 CFM (8.6V)
~18 dBA@1m
780 RPM
20 CFM

Our first fan is the Scythe Kama PWM, their only 120mm fan with a 4-pin PWM connector (they also have a 92mm model). It is also possibly the most important fan in this roundup due to the smaller number of PWM fans on the market. Some modern motherboards only provide fan control when used with PWM fans. While one can undervolt a 3-pin fan through a variety of methods, having the fan speed automatically adjust based on CPU or system temperature makes life a lot easier.

NOTE: We do not have a standard PWM fan speed controller for use in the lab, so comments here have to be limited to what we learned with our voltage controller. One result is that the fan's speed was artificially limited to a much narrower than usual range. We are in the process of selecting a suitable PWM fan speed controller for the future fan tests.

The Kama PWM is visually unremarkable. It has a fairly average hub size, seven large blades, and closed corners (not suitable for use with Thermalright clips or fan isolators without modification). The spokes are rounded to faciliate smoother airflow, but run almost parallel to the trailing edges of the fan blades, which will tend to produce tonal noise. This is in contrast to most of Scythe fans, whose struts are usually more or less perpendicular to the fan blade edges. The box comes with a molex adapter and simple fan screws.

Our sample had a high starting voltage of 7.2V — it simply will not spin up. This is directly related to its PWM design. Aside from that, the fan performed very well. At 9V, it produced 19 dBA and 21 CFM, placing it in very high on our list, second only to the Nexus Real Silent case fan. At high speeds, it growled a bit, but was very smooth otherwise. It also exhibited a slight clicking, but this was only audible very close-up and dissapeared below approximately 8.2V. During one test run, the fan began to chug at 9V — turning the fan off and re-monting it seemed to fix it. This was probably an anomaly.

For those seeking a PWM fan, the Scythe Kama PWM is an excellent choice. It has a narrow speed range with voltage control; it should have a much bigger range with PWM control. At full speed, it is a bit too loud for a silent PC. It's a good quality sleeve bearing fan, eseesentially what we have come to expect from Scythe.

Noise Recording

  • Scythe Kama PWM DFS122512L-PWM — 7.6V-8.1V-8.6V-9V-12V with 5s ambient between each level: One meter, at 20 CFM (8.6V)

SCYTHE SLIP STREAM SY122512SH

Ambient noise at the time of testing was 18 dBA.

Brand Scythe Power Rating 0.53A
Manufacturer Scythe Airflow Rating 110.31 CFM
Model Number SY1225SL12SH RPM Rating 1,900 RPM
Retail Availability Yes Noise Rating 37 dBA
Bearing Type Sleeve Header Type 3-pin
Hub Size 1.41" Starting Voltage 4.7
Frame Size 120 x 120 x 25 mm Number of Samples 2
Weight 120g Variance Noted See below
Voltage
Noise
RPM
CFM
12V
39 dBA@1m
1780 RPM
79 CFM
9V
26 dBA@1m
1340 RPM
54 CFM
7V
~18 dBA@1m
630 RPM
21 CFM
5V
<18 dBA@1m
400 RPM
12 CFM
@20 CFM (6.8V)
~18 dBA@1m
610 RPM
20 CFM

Next up, we have the Scythe Slip Stream Kaze Jyuni series. As with the Kama Flow line, they are sleeve bearing fans, but with a very different design. They have nine, fairly slim blades and spokes that curve in the opposite direction. The narrow hub size also maximizes the amount of air the blades can produce while minimizing the size of the dead spot at the center where the motor sits. The Slip Stream series comes in 5 different speeds ranging from 1900 to 500 RPM. All the Slip Streams include a molex adapter with RPM sensor (connected to a separate 3-pin header) and open corners, making them convenient for use on a CPU heatsink.

A key design element of the Slip Stream series is the geometry of the spokes. They are curved in such a way that at any point of the rotation arc, the edges of the blades meet each strut at only one point, in a near-perpendicular angle. This feature is designed to minimize tonal noise. It is not unique to the Slip Stream fans; they have been used on other fans in the past, but the design is not common. The only downside of these spokes is that the one which acts as a bridge for the wires is quite wide, and probably adds more turbulence noise than usual.

The SH (super high) model is a very high power fan, rated to draw 6.36W at 12V. At 12V it is very loud and whiney, but that was expected. It does however undervolt very nicely, dropping down to 26 dBA at 9V and ~18 dBA at 7V, making it inaudible at one meter in our lab. At 7V, it generated 21 CFM of airflow at a slightly lower noise level than the Kama PWM fan. At lower speeds it produced a bit of ticking. At close range, the overall motor noise was slightly higher than the lower speed Slip Streams, but still very quiet. A second sample exhibited some bearing chatter, possibly due to shipping or other damage. As we had only two samples, we are unable to confirm whether it was damaged or if the first sample was simply exceptional. We suspect the the "good" sample is how it is supposed to sound, judging from how the other Slip Streams sound.

The range of the SH variant, along with its ability to start up at 5V makes it very versatile. It can be a super high performance fan if your CPU is cranking away encoding video or and an almost silent one for when you're just lazily surfing the web.

Noise Recording

  • Scythe Slip Stream SY122512SH — 5V-6.8V-7V-9V-12V with 5s ambient between each level: One meter, at 20 CFM (6.8V)

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