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Scythe Katana 3: Same slant, new version

Scythe Katana 3

July 3, 2009 by Mike Chin

Product
Katana 3 CPU Cooler

Model SCKTN-3000
Manufacturer
Scythe
Sample Supplier
Anitec
Street Price
$26~30

Sometimes, Scythe's marketing copy is so amusing it's impossible to resist repeating it verbatim:

"The Japanese long sword 'Katana' is produced in a unique, manufacturing process, which has been brought to perfection over centuries - until today, only a few blacksmith master have the knowledge to manufacture a Katana. The new Scythe Katana 3 CPU cooler also arises from a consistent further development and differs from other CPU coolers and is a worthy successor to his precursors, Katana and Katana 2."

Even with the minor grammar issues, it's a heady brew. Not only does the copy neatly sidestep the question of what could possibly be exciting about a third version of a heatsink, it puts the Katana 3 in the glorious context of Japan's martial tradition and history. My hat is off to the marketing boys at Scythe.

Katana 3 is one of Scythe's least ambitious and most economical models. Among the giants and skyscrapers of the brand's extensive lineup, it stands out by being relatively small, light and inexpensive.



Full-color retail cardboard box in the Scythe tradition.

At least no
plastics are used in this one.

Scythe Katana 3: Key Features
(from the product
web page
)
Feature & Brief
Our Comment
Easy installation without any tools

The smart and patent-pending mounting mechanism "VTMS" (Versatile Tool-Free Multiplatform System) allows mounting of Katana 3 CPU heatsink without using tools.
Good, and secure enough with the low weight.
S.P.S. (Pipe Slant Structure)

Already developed with the first Katana, the slightly curved shape of the Katana 3 allows both the direct heat transfer from the cooling fins of the cooler as well as an additional cooling of the mainboard components.
It's a reasonable approach to the task of VRM cooling.
F.P.S. (Fast-Phase Structure)

The various cooling fins on the baseplate allow an additional heat dissipation and optimize the overall performance of the cooler without changing the compact dimensions of the entire system.
It's not clear whether this really helps, but the term sounds impressive. See text at bottom of p.2 for more discussion.


Scythe Katana 3: Specifications
(from the product
web page
)
Model #

SCKTN-3000

Heatsink
Dimensions
94 x 108 x 143 mm

3.70 x 4.25 x 5.63 inch
Weight
495 g (without accessory)

15.98 oz (without accessory)
Compatibility
- Intel LGA1366 (i7), LGA775, 478

- AMD AM2/2+/3, 939, 940, 754
Fan
Dimensions
92 x 92 x 25 mm
Weight
115 g
Speed
300 ~ 2,500 rpm (via PWM)
Noise Level
7.2 - 31.07 dBA
Bearing Sleeve Bearing
Air Flow
12 - 95 m³/h = 6.7 - 55.55 CFM

It's noteworthy that this modest heatsink is compatible for use with Intel's i7 processors. It is, in fact, compatible with almost every CPU socket type going back a decade. The reference to noise level is probably sound pressure level (SPL) at 1m.

PHYSICAL DETAILS



The Katana 3 comes with an installation guide, package of thermal interface material, and three sets of mounting hardware for all the various CPU sockets it supports.





The main bank of fins is tilted at an angle of about 30 degrees. Because it tilts over the base, the overall footprint remains relatively small. The main purpose of the tilt is to provide some airflow over hot components around the CPU socket. The 92mm fan is retained with two steel wire clips.




The fins are thin and spacing between them is fairly tight. Six heatpipes (actually three looped pipes) transfer the heat from the base into the fins. The secondary extruded aluminum piece over the base holds the mounting clips as well. It is what Scythe calls the Fast-Phase Structure.

The reason I question the supposed merits of Scythe's Fast-Phase Structure is that heatpipes are phase change devices that work best with high temperature differentials between the evaporator end and the condensor end. The hotter one end gets, the faster the internal liquid boils and turns to vapor, moving to the condenser end. Conversely, the cooler the other end gets, the faster the vapor turns back to liquid and moves down to the evaporator end. The extruded aluminum piece (FPS) is on the hot or evaporator end. Rather than being transferred up into the liquid of the heatpipes, some of the heat will go up to the FPS and be dissipated by airflow. This would reduce the total amount of heat going into the heatpipes, and it would have the effect of slowing down rather than speeding up the phase change process in the heatpipes. Have I missed something? Or has Scythe's marketingspeak gone one step too far?

Having said all that, if the mass of the FPS was converted into more fins on the main tower stack, the difference in CPU cooling would probably be marginal. The improvement in phase change speed would be offset by the absence of cooling via the extruded aluminum piece. It's just that Fast-Phase does not accurately describe the role of the secondary aluminum piece.

MORE DETAILS



There are effectively six heatpipes extending down into the base, but as mentioned above, they are actually three loops, with the center portiona sandwiched and soldered between the base and the secondary aluminum fins. The mounting hardware clips into the sides of the Fast-Phase structure; shown above are the AMD spring loaded clips, which work easily enough, with preloaded springs to apply a good (precisely calibrated?) amount of pressure. The base is smooth and flat.



These are the Socket 775 and
1366 arms with plastic locking pushpins, now in 1366 position. Slide each pushpin closer to the base and they fit into 775 socket.




The fan has good geometry for low tonal noise, with the blades' trailing edges nearly perpendicular to the struts throughout the rotation. It is a 4-pin PWM sleeve bearing fan rated to draw just 0.17A current at full speed, with claimed wide speed range of 300 ~ 2,500 rpm. The 7.2 - 31.07 dBA spec is promising as well.

INSTALLATION

The most critical aspect of installation is for the heatsink
to be securely mounted. The more firmly it is installed, the better the contact
between the heatsink's base and the CPU itself. It's also less likely to fall
off. Ease of installation is also important — a simple mounting scheme
means less time spent installing, and a reduced likelihood of screwing up.

The pushpins employed here for Intel 775/1366 socket boards work well enough. Access to the pins is unimpeded by the heatsink itself, and the total weight of 530g with fan and mounting hardware does not seem onerous for the plastic pins. The heatsink seemed quite firmly secured in the end.

For AMD processors, there is only one way that the Katana 3 can be mounted, but as most AMD boards have a north-south orientation for the heatsink retention frame, the fan ends up blowing in the right direction, towards the back of the case where there is usually an exhaust fan, rather than up towards the PSU intake (in a typical case).



Katana 3 set up and ready to go (without fan) on our Intel 775 socket heatsink testing board.

TESTING

Before thermal testing, we took some basic physical measurements.

Scythe Katana 3: Physical Measurements
Weight
530 g (with fan and mounting brackets)
Fin thickness
0.31 mm
Fin spacing
1.72 mm
Number of fins
48
Vertical Clearance
~55 mm (from
motherboard PCB to the heatsink's bottom fin)
Horizontal Overhang
-30 mm (that's 3cm in from
edge of heatsink to the top edge of our test motherboard)


Comparison: Approximate Fin Thickness & Spacing
Heatsink
Fin Thickness
Fin Spacing
Scythe Ninja 2
0.39 mm
3.68 mm
Thermalright HR-01 Plus
0.45 mm
3.15 mm
Noctua NH-U12P
0.44 mm
2.63 mm
Noctua NH-C12P
0.47 mm
2.54 mm
Prolimatech Megahalems
0.50 mm
2.00 mm
Xigmatek HDT-S1283
0.33 mm
1.96 mm
Cooler Master Hyper N520
0.38 mm
1.72mm
Xigmatek HDT-S963
0.33 mm
1.72 mm
Scythe Katana 3
0.31 mm
1.72mm
Thermalright Ultra-120
0.45 mm
1.42 mm

Testing was done according to our
unique heatsink testing methodology
, and the included fans were profiled
using our standard fan testing
methodology
. A quick summary of the components, tools, and procedures
follows below.

Key Components in Heatsink Test Platform

  • Intel
    Pentium D 950
    * Presler core, C1 stepping. TDP of 95W; under our test load, it measures
    78W including losses in the VRMs.
  • Asus P5Q-EM motherboard. A microATX board with integrated graphics
    and short solid-state capacitors around the CPU socket, and a diminutive northbridge heatsink for maximum compatibility.
  • Intel X25-M
    80GB 2.5" solid-state drive.
  • 1GB of Corsair XMS2 DDR2 memory. 2 x 512MB PC2-8500.
  • FSP Zen 300W
    fanless power supply.
  • Arctic Silver
    Lumière
    : Special fast-curing thermal interface material, designed
    specifically for test labs.
  • Nexus 92 fan (part of our standard testing methodology; used when
    possible with heatsinks that fit 92x25mm fans)
Nexus 92 fan measurements*
Voltage
Noise
Speed
12V
1240 RPM
9V
980 RPM
7V
770 RPM
* measured mounted on Katana 3

Measurement and Analysis Tools

  • Seasonic
    Power Angel
    for measuring AC power at the wall to ensure that the
    heat output remains consistent.
  • Custom-built, four-channel variable DC power supply, used to regulate
    the fan speed during the test.
  • PC-based spectrum analyzer:
    SpectraPlus with ACO Pacific mic and M-Audio digital
    audio interfaces.
  • Anechoic chamber
    with ambient level of 11 dBA or lower
  • Various other tools for testing fans, as documented in our
    standard fan testing methodology
    .
  • SpeedFan, used to monitor the on-chip thermal sensor. This sensor is not
    calibrated, so results are not universally applicable.
  • CPUBurn
    P6
    , used to stress the CPU heavily, generating more heat than most
    real applications. Two instances are used to ensure that both cores are stressed.
  • Throttlewatch
    2.01
    , used to monitor the throttling feature of the CPU to determine
    when overheating occurs.

Load testing was accomplished using CPUBurn to stress the processor, and the
graph function in SpeedFan was used to make sure that the load temperature was
stable for at least ten minutes. The stock fan was tested at various voltages
to represent a good cross-section of its airflow and noise performance.

*An Aside: Pentium D at 130W TDP?



The low 78W (minus VRM losses) drawn by our Pentium D 950 chip has been a curious oddity since we began using it on our heatsink test platform a few years ago. As far as we knew, it was supposed to have a TDP of 130W; we assumed ours was an exceptionally cool sample. Recently, curiosity followed its inevitable course: Web research after identifying the exact details of our Pentium D — model 4, stepping 4, revision C1, 12+16kB/2048kB L1/L2 cache, 'Presler' FSB200x4, XD, VT, EIST. It turns out there were two main versions of the Pentium D. Ours was the last iteration, not surprisingly, the most energy efficient. The C1 stepping identified it on Intel's Processor Spec Finder database as a Presler core with 95W TDP, not the 130W we'd always thought. At less than 78W at full tilt, it still seems like an exceptionally cool running processor.

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
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 [email protected] 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
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 [email protected], 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 [email protected]

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 [email protected]

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.

MP3 SOUND RECORDINGS

These recordings were made with a high
resolution, lab quality, digital recording system
inside SPCR's
own 11 dBA ambient anechoic chamber
, then converted to LAME 128kbps
encoded MP3s. We've listened long and hard to ensure there is no audible degradation
from the original WAV files to these MP3s. They represent a quick snapshot of
what we heard during the review.

These recordings are intended to give you an idea of how the product sounds
in actual use — one meter is a reasonable typical distance between a computer
or computer component and your ear. The recording contains stretches of ambient
noise that you can use to judge the relative loudness of the subject. Be aware
that very quiet subjects may not be audible — if we couldn't hear it from
one meter, chances are we couldn't record it either!

The recordings start with 7~10 second segments of room ambiance, then the fan
at various levels. For the most realistic results, set the volume so that
the starting ambient level is just barely audible, then don't change the volume
setting again.

FINAL THOUGHTS

The Scythe Katana 3 delivers cooling performance that's good enough for most mid-power CPUs (~65W TDP). Its stock fan is decently quiet, and with a good on-board PWM fan controller, could provide essentially inaudible cooling for a midrange PC. The dreaded plastic push-pins for socket 775/1366 boards are easy to use here, as access to the pins is good. Its low weight makes the push-pins safe; there's no risk of them popping out or breaking under undue strain. Even though the AMD clip doesn't allow for heatsink or fan rotation, on most AMD boards, the fan will end up blowing in the right direction, toward the back case exhaust fan.

Whether the down-angled fan helps with VRM or northbridge cooling was not possible for us to assess. With mid and lower power CPUs, the need for such cooling is probably not critical, but our basic perspective is that it certainly can't hurt.

The support for socket 1366 is an amusing touch, and made possible because it's just an integral part of the Katana 3 socket 775 mounting bracket. Could the Katana 3 cool a 130W TDP i7 processor effectively? Well, with the fan at or close to full speed, probably, but it would hardly be a quiet solution.

Scythe Katana 3 does not pretend to be a giant killer (or cooler), but does a fine job of quietly cooling a mid-power processor. It is easy to install and use on any current CPU socket. Best of all, its modesty also extends to price: US$26~30.

Scythe Katana 3
PROS



* Good cooling for midpower CPU

* Nice fit and finish


* Quiet PWM fan

* Price

CONS



* No fan controller supplied?

Our thanks to Vanvouver retailer Anitec for the Scythe Katana 3 sample.

* * *

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Xigmatek HDT-SD964



Thermaltake BigTyp 14Pro: A Bigger Typhoon

Zalman CNPS9900 LED: The End of the
Nines

ThermalTake SpinQ: Unique Blower-fan
Heatsink


Thermolab Baram Blows In

Scythe Ninja 2: Tweaking a Classic

Zalman 9300AT: Not me too, but
me again


* * *

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