Scythe Katana 3: Same slant, new version

Cooling
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TEST RESULTS

The Fan

Some basic measurements were made of the Scythe SY9225SL12M-P fan included with Katana 3.

Fan Specifications
Brand Scythe Power 0.17A (2W)
Model SY9225SL12M-P Airflow 6.7 - 55.55 CFM
Bearing sleeve RPM 300~2500
Hub Size 34mm (1.32") Noise 7.2 - 31.07 dBA
Frame Size 92 x 92 x 25 mm Header 4-pin
Weight 115 grams Start Voltage ~7.5V
The data in the blue cells is provided by the manufacturer; we measured the data cited in the green cells

FAN MEASUREMENTS
Voltage
SPL - dBA@1m
RPM
free air
mounted
12V
32
34
2600
10V
27
28
2250
9V
22
23
1900
8V
16
16
1520
7.5V
11
11
830

Regular readers will notice that the measurement points are not at the usual 12, 9, 7 and 5 volts. This PWM fan, like many others, does not have as linear a relationship with voltage as normal DC fans. The range of speeds controllable via voltage is only about 1400~2600 rpm, and by 7.5V, the fan does not start reliably. Via PWM control in our motherboard BIOS, speeds well below 1400 rpm were seen, and we have no reason to doubt the 300 RPM minimum speed. The fine control of a knob is not available on our motherboard's BIOS fan controller, so there was no easy way of tagging the SPL at lower speeds. Suffice it to say that 16 dBA@1m is very quiet, and given the smooth quality of this fan, the noise at lower speeds will be essentially inaudble under most conditions.

When mounted on the heatsink, the fan exhibited a bit more noise than in free air, and the difference became smaller as fan speed was reduced. This is normal; it's the increased turbulence caused by the fan blades' close proximity to the fins which causes this effect.

Sound Impressions

@ 12V: The noise was mostly broadband turbulence, with some high pitched tonal elements. It was not terribly loud, but too loud to be considered quiet.

@ 10V: The overall level dropped substantially, and the sound stayed smooth, but some tonal traces remained. Still not exactly quiet.

@ 9V: The noise dropped to a point where many users would find it quiet enough to ignore. Some tonality still remained, although inside a decent case with other noise source, it would probably be obscured and blocked.

@ 8V: Very subdued in level, smooth and unobtrusive, probably inaudible in a good case under most conditions for most people. A touch of tonality was still audible from up very close.

The tonal aspects of the noise seem to be caused by the interaction of the fan's vibrations and airflow, and resonances in the fins. It's possible that adding damping material between the fan and the heatsink could reduce the tonality, because the fan by itself in free air exhibits little of the tonal traces described above.


Cooling Results

Scythe Katana 3: Stock Cooling Performance
Fan Voltage
SPL dBA@1m
CPU Temp °C
°C Rise
°C/W
12V
34
39
15
0.19
10V
28
40
16
0.20
9V
23
41
17
0.22
8V
16
44
20
0.26
Scythe Katana 3 w/ reference 92mm fan
12V
17
42
18
0.23
9V
13
47
23
0.30
7V
11
50
26
0.33
Load Temp: Prime95x2 for ~10 mins.
°C Rise: Temperature rise above ambient (24°C) at load.
°C/W: based on the amount of heat dissipated by the CPU (78W); lower is better.

The Scythe Katana 3 performed quite well, with a temperature rise of 15°C at full fan speed, and dropping by small increments as the fans was slowed. In stock form, at the slowest speed we could test at, with the noise level at just 16 dBA@1m, the rise above ambient was just 20°C. This is excellent performance for a heatsink of this size.

With the quieter, slower Nexus reference fan, the cooling performance was not quite as good, but the noise could be dialed down even further. The cooling performance remained acceptable down to ~13 dBA@1m.

COMPARISONS

When judged on noise vs. cooling, Katana 3 fares well against most other stock heatsink/fan combos of similar size SPCR has tested. Here's a quick comparison against a few heatsinks with stock fans at around 23~24 dBA@1m.

Comparison: With Stock Fans at 12V
Heatsink
°C rise
SPL
ZEROtherm CORE92
12
20 dBA
Zalman CNPS9300 AT
15
24 dBA
Scythe Katana 3
17
23 dBA
Cooler Master Hyper N520
19
23 dBA
Xigmatek HDT-SD964
20
21 dBA
Thermaltake MaxOrb
21
24 dBA

How close is the Katana 3 to the very best silent coolers? Not very close, like most of its direct competitors. But it's neither as big nor as costly.

°C rise Comparison: The Best of the Best
Heatsink
Nexus 120 fan voltage / SPL @1m
12V
9V
7V
5V
16 dBA
13 dBA
12 dBA
11 dBA
Prolimatech Megahalems
10
14
17
20
Thermalright U120E
12
14
17
24
Thermalright HR-01+
13
15
16
20
Xigmatek HDT-S1283
13
15
18
22
Noctua NH-U12P
14
16
17
21
Zalman CNPS10X Extreme
14
17
21
26
Zerotherm Zen FZ120
15
16
19
24
Scythe Ninja 2
17
18
20
23
Thermolab Baram
18
20
22
25
All results generated with our reference Nexus 120mm fan.



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