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Ambient noise at the time of testing was 18 dBA. This ambient level was the same for every test conducted for this review.
||12.38 ~ 52.71CFM
||Immeasurable ~ 24.89 dBA
||120 x 120 x 25 mm
||Number of Samples
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
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.
- 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.
||120 x 120 x 25 mm
||Number of Samples
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
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
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.
- 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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