Scythe Katana

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This new budget heatsink from Scythe has many desirable features:

* Long copper heatpipes married to thin alumimum fins
* Good quality modest noise fan
* Mountings for sockets 478, 775, K8, 370 and A
* Very light weight
* Angled, rather than perpendicular to motherboard

Our review of this latest “blade” from Scythe.

October 2, 2005 by Devon
Cooke
and Mike Chin

Product

Scythe Katana CPU Heatsink with Heatpipes

Supplier

Scythe USA

Price
~US$30

Scythe is one of the most prolific heatsink makers
on the market. At present, their web site lists no less than ten different coolers
from the Scythe brand. These products cover almost every conceivable
market niche for heatsinks, from cheap $20 heatsinks to the massive (and expensive)
Ninja, which has the potential to cool almost any CPU passively. You have to
wonder whether Scythe gives any thought at all to the target market for their
products, but you certainly can’t argue with the choices they offer. The only
downside is knowing which one to pick!

The Scythe Katana won’t be competing with the Ninja for the performance crown,
but it’s much more reasonable in size and price. Its light weight and universal
compatibility make it useful in situations where a larger heatsink
cannot be used.


A full color box to keep the retailers happy, but it’s no larger than
it needs to be.


Included in the box: The heatsink with the fan pre-mounted, installation
hardware, and installation instructions.


Scythe Katana: Feature Highlights (from the
product web page
)

Feature & Brief

Our Comment
Super Light Weight & Compact Heatpipe CPU Cooler
With 92mm fan attached on the Katana CPU Cooler, it overall weight is
ONLY 300g! This cooler is ideal for both users seeking for an upgrade
for their current CPU or for systems builder to integrate into their PC
systems to build a silent PC systems.
300 grams is probably the lightest aftermarket heatsink we’ve ever
seen. Ideal for systems that are frequently moved, such as a LAN Party
system.
Universal Socket Compatibility
Katana CPU Cooler is compatible for socket 370/462/478/754/939/940 &
the new LGA775. All in one solution for your PC system!
Compatible with all modern processors,
and can even be used with old Celerons, P-IIIs and AMD’s Socket A processors.
Low-Noise 92mm Fan
Supplied 92mm fan rotates at only 2000rpm providing only 25dBA of noise,
this cooler is an ideal solution for low-noise PC systems.
Low noise sounds good to us, but we’ve learned to be sceptical about
these claims. We’ll have to test it to find out…
Cooling the Mainboard Components
With the unique angle (70 degree) construction of the Katana CPU Cooler,
the cooler can also cool the components on the mainboard to prolong its
life and keep your PC system stable (subject to fan mounting & airflow
direction).
Both AMD and Intel thermal guidelines state that
the CPU fan should also cool the VRMs around the CPU socket. Most tower-style
heatsinks do not follow this guideline, but Scythe has made an effort to
do so. Whether the effort is successful is harder to say.
4-Way Mountable Design to Optimize the Cooling
With the special mounting clips provided with Katana CPU Cooler, users
are able to mount this cooler in the best position based on the airflow
and set-ups inside the PC case. (For socket 370/462, limited to 2-way
mountable design)
This means the heatsink can always be mounted with the fan blowing
in the right direction — something that is not always possible with
tower heatsinks.

Based on the feature set alone, the Katana has a number of desirable qualities.

Its low 300 grams mass is incredible, only two thirds of Intel’s recommended
450 gram limit for heatsinks. Many other heatsinks exceed this limit by 200
grams or more, and some all-copper designs weigh over a kilogram! The low
weight means it does not suffer from the two major risks associated with heavy
heatsinks: Stressing and warping the motherboard, and coming loose during transportation.

Some of the problems common to tower-style heatsink with the fan blowing across the CPU have
been addressed:

It can be mounted in any orientation, meaning that there are
no situations where the airflow cannot be directed towards the rear system fan.
Note that Socket 370 and Socket A (462) do not have this advantage (of being rotated to any position), so if you
have an older system you will still need to be careful.

Some airflow over the motherboard voltage regulators
is achieved by tilting the heatsink slightly.
This is an improvement
over most tower heatsinks, which typically do not provide any airflow for the
motherboard. It is still inferior to the traditional downward-blowing
heatsinks, most of which can provide cooling on at least two sides of the CPU.


Scythe Katana Specifications (from the
product web page
)
Model Name Katana CPU Cooler
Manufacturer Scythe Co. Ltd., Japan
Compatibility Intel
Celeron (socket 370) all speeds
Celeron (socket 478) all speeds
Pentium III (socket 370) all speeds
Pentium 4 (Socket 478) all speeds
LGA775 (Socket 775) all speedsAMD
Duron (socket 462) all speeds
Sempron (socket 462) all speeds
Athlon (socket 462) all speeds
Sempron (socket 754) all speeds
Athlon 64 (socket 754) all speeds
Athlon 64FX (socket 754) all speeds
Opteron (socket 939) all speeds
Opteron (socket 940) all speeds
Fan Dimensions 92 x 92 x 25 mm
Combined Dimensions 98 x 96 x 130 mm
Fan Speed 2000 RPM (±10%)
Fan Noise Level 25.0 dBA (no distance specified)
Airflow 35.12 CFM
Weight (with Fan) 300 g

Scythe really has gone for universal compatibility; even socket A and 370 are supported. Note that 300 grams is AMD’s maximum recommended mass for socket A. (The only current processor not listed is the Pentium M, which does not
have a standard mounting form factor for desktop use. Many Pentium M boards utilize
mountings similar to other sockets, so compatibility will depend on the motherboard
more than the heatsink.)

Like most tower heatsinks, the Katana uses copper heatpipes to
transfer the heat away from the CPU. The base is also copper, but the
fins are made of aluminum. The fins are
quite easily bent because they are so thin.

In comparison to the most ambitious tower-style heatsinks, the fins are considerably smaller. Most of the reduction in size comes
from the depth of the fins — the heatsink is only about an inch and a half
thick. Although the small surface area will hurt cooling efficiency, it’s well-suited for use with a low speed fan, as the airflow impedance should
be quite low.


The fins have a slight "double wave" — no straight edges
here.

For some reason, both faces of the heatsink are doubly contoured,
which further reduces the surface area. On the side with the fan, this should
help reduce backpressure and the associated turbulence noise, but it is unclear
what benefit this has on the opposite side. Perhaps it helps lengthen the edges
of the fins or perhaps the third "corner" at the center of the fin
draws heat away from the heatsink.


The Katana uses a "leaning tower" design to direct airflow slightly
downwards.

The most unusual aspect of the Katana is its 20° tilt
from the vertical axis. As mentioned above, this is supposed to help cool
the components around the CPU socket, but it also has another benefit. Mounting
the fan on the upper side of the heatsink means that there is more clearance
above any tall components around the CPU socket, so tall capacitors and RAM
should not be an issue.


The included 92 mm fan is almost exactly the same dimensions as the heatsink
underneath.

The 92 mm fan is attached to the heatsink with two wire clips. Initially, the tension was quite high, and it was difficult to remove the clips. However, the clips
stretched a bit with a few uses and by the time the test was conducted, they longer kept the fan under high tension. This meant
that the fan could potentially rattle against the fins, although we did not
encounter this problem with the low speed fans that we used during our testing.


The base is typical of a heatpipe-based design: A small polished copper
square to which the heatpipes are clamped.

The image above shows a metal socket 478 mounting adaptor
attached with four screws.

INSTALLATION

The Katana ships with a huge
amount of specialized hardware. Determining which bits of
hardware you need to use requires close attention to the instruction sheet,
which has separate instructions for each socket. Like every other Scythe product
we’ve seen, the Katana instruction sheet is full of small densely packed text, and
more than one mounting procedure is listed on the same page. It’s easy to accidentally
start reading the wrong section in the middle of an installation, causing unwarranted
confusion.

Our test bed uses a socket 478 processor, so installation was tested
for this socket only. The mounting system is similar to some of Scythe’s other
heatsinks, notably the Shogun. The first step is to screw on a mounting plate.
Depending on the orientation that you need, this place will be either a single
plate that fits over the base, or two "wings" that screw onto either
end.


An awkwardly placed machine screw must be tightened to put the heatsink
under tension.

Next, the heatsink is settled into place inside Intel’s stock retention module.
Two metal bars are threaded through the retention module on either side of the
heatsink, and then a single machine screw on each bar is tightened. The threaded
end of the screw does not actually screw into anything but rests in a small
dimple in the baseplate. When the screws are tightened, the metal bars are forced
upwards against the retention module and the baseplate is securely wedged against
the processor. We have no complains about the security of this mounting system.

The trouble with this screw-based mounting is that the screw heads end up directly
underneath the fins and require a special wrench (included) to be tightened.
To make matters worse, the position of the northbridge heatsink on our test
board (see the photo above) made it difficult to fit the wrench over the head
of the screw. Tightening the screw was a tedious affair, as we could only turn
it about a sixth of a turn at a time.

The mounting procedure requires that the motherboard be out in the open with clearance on two sides of the CPU socket. If the motherboard has a large heatsink on the northbridge chip, the Katana probably cannot be used due to the position of the tensioning mounting screw.

Installation for Other Sockets

LGA775: This calls for a couple of additions to the 478 mounting plate on the hetasink, plus installation of two steel brackets that basically convert the LGA mounting setup into a socket 478 retention bracket. The cautions and limitations about access to the mounting screws noted for socket 478 installation apply here as well.


For socket 775

K8: For current AMD sockets (754, 939, 940), a different addition is made to the 478 mounting plate on the HS. Two spring-loaded machined screws are used to mount the heatsink. If the motherboard does not have a CPU socket backplate, the supplied metal one can be used. Access to the mounting screws might be a little easier here than with socket 775 or 478… but maybe not.


For socket K8

370 & 462: Just the heatsink is needed, without any attachment on the base. An old fashioned 6-point hook is used. This is probably almost as easy as installing a stock heatsink.


For sockets 370 and A

Finally, there is a caution regarding the "Proper Direction for the Installation". Three of the four mounting positions are OK; the fourth, which causes the ends of the heatpipes to be pointing downward, is not approved. This has to do with the need for grvitational pull to flow the condensed liquid in the heatpipes back to the base.

TESTING


On the test bench…

Test Platform

  • Intel
    P4-2.8A
    The Thermal Design Power of this P4-2.8 (533
    MHz bus) is 68.4 or 69.7W depending on the version. As the CPU is a demo model
    without normal markings, it’s not clear which version it is, so we’ll round
    the number off to ~69W. The Maximum Power, as calculated by
    CPUHeat
    & CPUMSR
    , is 79W.
  • AOpen
    AX4GE Max
    motherboard – Intel 845GE Chipset; built-in VGA. The on-die
    CPU thermal diode monitoring system reads 2°C too high, so all readings are
    compensated up by this amount.
  • OCZ
    DDRAM
    PC-3200, 512 MB
  • Seagate Barracuda IV 40G 1-platter drive (in Smart
    Drive
    )
  • Seasonic
    Super Tornado 300
    (Rev. A1)
  • Arctic Silver
    Ceramique
    Thermal Compound
  • Nexus
    Real Silent
    92mm fan
  • Two-level plywood platform with foam damping feet. Motherboard on
    top; most other components below. Eases heatsink changes and setup.

Measurement & Analysis Tools

  • CPUBurn
    processor stress software
  • SpeedFan
    version 4.25
    software to show CPU temperature
  • A custom-built fan controller that allows us to dial in exactly what voltage
    is powering the fan

Noise and airflow measurements were made with the fan powered from the fan
controller while the rest of the system was off to ensure that system noise
did not skew the measurements. The Katana was tested both with its stock fan
and our standard 92mm reference fan, a Nexus. Airflow measurements were made
while the fans were mounted on the heatsink, and are lower than they would be
if they were measured in free air.

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 ambient conditions during testing were 18 dBA and 24°C.

TEST RESULTS

Scythe Katana with Stock
Fan
Fan Voltage
Airflow
Load Temp
°C Rise
°C/W MP
°C/W TDP
Noise
12V
25 CFM
47°C
23
0.29
0.33
33 dBA/1m
9V
21 CFM
49°C
25
0.32
0.36
26 dBA/1m
7V
16 CFM
51°C
27
0.34
0.39
22 dBA/1m
5V
11 CFM
54°C
30
0.38
0.43
~19 dBA/1m

Airflow: Measured in Cubic Feet
per Minute mounted on the HS
Load Temp:
CPUBurn for ~20 mins.
°C Rise: Temperature rise above ambient at load.
°C/W MP / TDP: Temperature rise per Watt, based on CPU’s Maximum
Power (79W) or Thermal Design Power (69W) rating (lower is better)
Noise: SPL measured in dBA/1m distance with high accuracy B &
K SLM

12V / 25 CFM: The stock fan Katana is quieter than most heatsinks at full speed
but is still too loud to really be called quiet. The cooling performance at
this level is perfectly acceptable for our CPU, which means it is adequate for
most AMD based systems. Current AMD CPUs dissipate about as much heat as our
2.8 GHz Northwood, with the high end models getting a bit hotter. However, Intel’s more recent Prescott and Pentium D processors
run much hotter, and will probably require more cooling than the Katanda can provide. We can extrapolate that a CPU with
a 115W TDP, such as the high end Pentium 6xx models, would see a 38°C
rise over ambient.

9V / 21 CFM: Dropping the fan voltage to 9V makes a dramatic difference
to the noise level, which was measured at 26 dBA/1m. The load temperature
only rises by 2°C, so the reduction is well worth the thermal penalty.

At this level, the fan is quiet but not silent, so the quality of the noise
is quite important. Most of the noise comes from the motor, which gives off
a soft hum somewhere around middle C. A tiny amount of buzz from the bearings
can be heard on close listening, but otherwise the sound is very clean and
constant.

7V / 16 CFM: For another 2°C rise, the fan noise can be reduced
to a level that should be around ambient in most environments, although it
is still clearly audible in our lab. The noise character doesn’t change much
except for the lower volume and the lower pitch of the motor hum. The hum
is very slightly rougher, but not enough that it will be clearly audible once
it is installed in a case. Most users should be happy with the noise level
at 7V, and the performance is still good enough for most AMD-based systems,
although a system with poor airflow may have problems.

5V / 11 CFM: At 5V, the fan is around the ambient noise level in our
lab, which means it should be more or less silent once it is installed in
a case. A trace of motor hum can still be heard if you put your ear up to
it, but it is almost as quiet as the light buzz from the bearings. Performance
at this level is beginning to suffer a bit; the CPU is now 7°C warmer
than the temperature with the fan at 12V. Most users will not see much acoustic
benefit undervolting past 7V as it is likely to be below the ambient noise
level — or the louder components in their system.

Scythe Katana with Nexus
Reference Fan
Fan Voltage
Airflow
Load Temp
°C Rise
°C/W MP
°C/W TDP
Noise
12V
20 CFM
51°C
27
0.34
0.39
23 dBA/1m
9V
14 CFM
53°C
29
0.37
0.42
20 dBA/1m
7V
11 CFM
57°C
33
0.42
0.48
<19 dBA/1m
5V
7 CFM
66°C
42
0.53
0.61
<19 dBA/1m

Airflow: Measured in Cubic
Feet per Minute mounted on the HS
Load Temp:
CPUBurn for ~20 mins.
°C Rise: Temperature rise above ambient at load.
°C/W MP / TDP: Temperature rise per Watt, based on CPU’s Maximum
Power (79W) or Thermal Design Power (69W) rating (lower is better)
Noise: SPL measured in dBA/1m distance with high accuracy B &
K SLM

Our reference Nexus fan is even slower and quieter than the stock fan, so the
results are somewhat higher temperatures and lower noise. However, when the two
fans are compared at the same airflow, the noise levels are very similar,
and it is difficult to say which fan is quieter at a given speed. Because
the Nexus is a slower fan, its can potentially be even quieter than the stock
fan, but very few users are likely to notice the difference since even the stock
fan will be below ambient most of the time.

One thing that is noticeable is that cooling performance
drops off rapidly when airflow drops below ~11 CFM, which means that running
the Nexus fan at 5V is impractical for most users. The load temperature
jumps 9°C when the fan is dropped to 5V from 7V, whereas the drop to 7V
from 9V caused only a 4°C rise. The performance-for-noise "sweet spot"
is right around the point when the stock fan is running at 5-7V: The noise level
is near ambient, but the cooling performance is still not bad.

COMPARISONS

Two other inexpensive heatsinks
were chosen for the comparison: The Arctic
Cooling Super Silent 4 Ultra TC
, and Scythe’s
own Kamaboko
. These heatsinks can be had for US$30 or less, and
they use 92mm fans. The data for the comparison comes from the two reviews linked
to above. Note that neither the Super Silent 4 nor the Kamaboko was tested using
the Nexus fan, so the comparison is between each of these heatsinks in stock
form. To make a fair comparison, data points close to
22 dBA/1m were chosen.

Heatsink Comparison by Noise
Heatsink
Noise
°C Rise
°C/W MP
°C/W TDP
Airspeed
Scythe Katana
22 dBA/1m
27
0.34
0.39
16 CFM
Scythe Kamaboko
20 dBA/1m
34
0.43
0.49
16 CFM
Arctic Cooling Super Silent 4 Ultra TC
22 dBA/1m
39
0.49
0.57
N/A

The Katana is clearly superior to either of the other two heatsinks at this
noise level. However, it is worth noting that the Super Silent 4 Ultra TC is
thermally controlled, so it will increase the fan speed — and noise —
as necessary to keep the processor cool.

It is also interesting to note that the airflow and fan voltage are the
same for the two Scythe heatsinks, suggesting that the two fans are identical.
Listening to the recordings of the two heatsinks side by side reveals that they
have slightly different noise signatures, however. The stock fan on the Kamaboko
may be very slightly quieter at 7V than the Katana.

NOISE RECORDINGS

Scythe Katana with Stock Fan:

MP3:
Scythe Katana – 12V – 25 CFM / 33 dBA/1m

MP3:
Scythe Katana – 9V – 21 CFM / 26 dBA/1m

MP3:
Scythe Katana – 7V – 16 CFM / 22 dBA/1m

MP3:
Scythe Katana – 5V – 11 CFM / ~19 dBA/1m

Recordings of Comparable HSF:

MP3: Nexus
92mm Fan – 12V – 23 dBA/1m

MP3: Nexus
92 Fan – 7V – <19 dBA/1m

MP3: Arctic
Cooling Super Silent 4 Ultra TC, 22 dBA/1m

MP3: Scythe
Kamaboko – 7V – 20 dBA/1m

HOW TO LISTEN & COMPARE

These recordings were made with a high
resolution studio quality digital recording system. The microphone was 3″ from
the edge of the fan frame at a 45° angle, facing the intake side of the fan to
avoid direct wind noise. The ambient noise during all recordings was 18 dBA or
lower. It is best to download the sound files to your computer before listening.

To set the volume to a realistic level (similar to the original), try playing this Nexus 92mm case fan @ 5V (17 dBA/1m)

recording and set the volume so that it is barely audible. Then don’t
reset the volume and play the other sound files. Of course, all tone
controls and other effects should be turned off or set to neutral. For
full details on how to calibrate your sound system playback level to
get the most valid listening comparison, please see the yellow text box
entitled Listen to
the Fans
on page four of the article
SPCR’s Test / Sound Lab: A Short Tour.

FINAL CONCLUSIONS

The Scythe Katana is a worthy addition to the
Scythe line. It does
well in comparison to some of the other sub-$30 heatsinks we’ve tested.
Its stock fan is very quiet once it is slowed down, making it a decent choice
for a midrange system. For hot high-end processor, however, a bigger,
more expensive heatsink is probably required.

Apart from its cooling and noise performance, there are a number of notable features.

  • The light
    weight of the heatsink makes it totally safe to transport while mounted on a motherboard in a system. The Katana could find a good home in a
    midrange gaming system for LAN parties, althought it is too tall to fit
    most SFF systems.
  • It’s probably the best heatsink currently made for socket A / 370. Fit could be a problem in some motherboards, but it looks reasonably compatible with a lot of socket A and 370 boards.

As with most Scythe heatsinks, the main problem with the Katana is the complex installation procedure. Installing
it on our test system proved to be quite tedious thanks to the awkwardly placed
mounting screws and the need to use that tiny supplied wrench to tighten it. In fact, the mounting system (for all the platforms except socket 370 and socket A) could be described as the Katana’s Achilles’ Heel.

The Katana is a good choice for a silent midrange system,
where money is a concern. The only drawback is that a Zalman Fanmate may need
to be included in the cost so that the fan can be slowed down.

Pros

* Stock fan undervolts well
* Low price
* Universal socket compatibility
* Light weight
* Cooling for voltage regulators
* Heatsink can be installed in most any orientation

Cons

* Fiddly installation;
* Possible bad access to mounting screws on many modern motherboards
* Instruction sheet poorly laid out
* Fan clips prone to stretching

Much thanks to Scythe
USA
for the Katana sample.

* * *

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