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Scythe Mugen-2 CPU Cooler

Scythe Mugen-2

July 15, 2009 by Lawrence Lee

Product
Scythe Mugen-2

CPU Cooler
Manufacturer
Scythe
Street Price
US$35~$40

The Scythe Mugen-2 is the updated version of the
Mugen
(AKA Infinity) CPU cooler. At the time of its release, the Mugen
was an excellent heatsink, able to cool most of the processors of its day with
little airflow. Unfortunately the Mugen coexisted with the better performing Scythe
Ninja
, which took most of accolades. The heatsink itself has had some interesting design improvements and now comes with a 120mm PWM fan. Most importantly, this big heatsink sports a simple
bolt-thru installation procedure. It is Scythe's first serious departure from stock Intel plastic push-pins in many years.



The box.





Box contents.

While Scythe practically invented the massive CPU heatsink, most of them use
stock LGA775 pushpin and AMD tension-clip mounts. These mounting methods are fine for
regular-sized coolers, but peace of mind quickly goes out the window in the
face of gravity acting on a 15-16cm tall aluminum/copper tower weighing almost
1kg and sitting on a processor worth hundreds of dollars. With the Mugen-2, installation
on any of the compatible sockets requires the heatsink to be bolted down with steel machined screws to a spider-like steel backplate. This is a major improvement over plastic push-pins and stock mounting clips.



The Scythe Mugen-2.


Scythe Mugen-2: Key Features
(from the product
web page
)
Feature & Brief
Our Comment
F.M.S.B. (Flip Mount Super Back-Plate)

The newly developed F.M.S.B. (Flip Mount Super Back-Plate) both improves
the compatibility and mounting of the cooler with the motherboard. With
this system, a solution was developed which is not using push pins but is
instead based on a Back Plate/screws mounting set. Of course, Mugen-2 is
compatible with all the current sockets, including the new Intel Socket
LGA1366.
The Mugen-2 is the first Scythe CPU cooler
to feature a straight bolt-thru mounting design. A single backplate offers
hard mounting for all modern Intel and AMD sockets.
Multi Fan Mount Structure

As with the former Mugen it is possible to mount the supplied fan in four
different directions. By this, the user can arrange the air flow to the
circumstances of his deployment area. Furthermore, a maximum of 4 fans
be installed, the needed fan clips have to be bought separately.
Like the Ninja series, fans can be installed
on all or any of the four sides. The Mugen-2 is not a perfectly square
heatsink, though, so fans placed on the narrow sides will not perform as
well.
M.A.P.S. (Multiple Airflow Pass-Through
Structure)


The newly developed M.A.P.S. (Multiple Airflow pass-through structure) is
a completely new lamellar structure, where the airflow generated by the
Scythe Slip Stream 120 mm PWM fan can be used perfectly
Mugen-2 has a series of slits running
down the length of its mass, effectively splitting the fins in into five
columns. This feature has been implemented to reduce resistance to airflow.


Scythe Mugen-2: Specifications
(from the product
web page
)
Model Name: MUGEN-2
Model #: SCMG-2000
Manufacturer: Scythe Co., Ltd. Japan
Heatsink
Dimension: 130 x 100 x 158 mm

51.2 x 39.4 x 62.2 inch
Weight: 870 g, 30.7 lb
Baseplate-Material: Nickle-plated copper
Compatibility IntelLGA1366

IntelLGA775 (SocketT)

Intel Socket 478 Processor


AMD Socket AM2+

AMD Socket AM2 Processor


AMD Socket 940 Processor


AMD Socket 939 Processor


AMD Socket 754 Processor
Fan
Dimension: 120 x 120 x 25 mm

4 3/4 x 4 3/4 x 1 inch
Weight: 115 g, 0.25 lb
Speed: 324 ~ 1,200 rpm (±10%)

PWM Function
Noise Level: 0 - 26.50 dBA
Air Flow: 0 - 74.25 CFM, 0 - 126 m³/h
Bearing: Sleeve

PHYSICAL DETAILS



Compared to the Ninja 2, the Mugen-2 is a bit taller and has more surface
area due to tighter fin spacing. The heatpipes also spread out further
giving the heatsink a larger wingspan — the heatsink's width
exceeds the size of the fan meant to cool it.



The fins measure 0.31 mm thick with an average spacing of 1.89 mm. The
fins are laid out in a standard flat array, rather than the interleaved
pattern of the original Mugen.




Most of the fin layers are actually composed of five separate pieces of aluminum. As a result, four slits run through the heatsink between the heatpipes. This helps air
flow through more easily from one side to the other, which is particularly useful when the fan speed is low. It also exposes an extra 10 edges for each fin layer, which can improve heat dissipation. (Editor's Note: Several fin layers do extend across all the heatpipes; they are like the bottom piece shown in the photo below. They serve to provide rigidity to the overall structure without adding any significant impedance to the airflow through the fins.)




The Mugen-2 has a nickel-plated copper base like the rest of Scythe's
recent heatsinks. The bases of the Mugen and
Ninja originals were not plated.



The base is flat and the finish is just short of mirror quality.


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 Mugen-2 is the first of Scythe's heatsinks to offer a proper
bolt-thru mounting system. First a set of mounting brackets is screwed
onto the base.




Unfortunately installation requires bolts to be secured from the back
of the motherboard. Furthermore, the backplate does not stay put. Applying
tape to hold it in place is a good temporary solution.




Only the bottom half of the bolts are threaded, ensuring uniform tension: You simply screw down until the thread stops. The installation procedure for LGA1366
and AMD boards is similar.





Mounted in our test system with fan installed (backwards — ooops!)
on our LGA775 test board. On AMD motherboards the Mugen-2 mounts in
the same orientation pictured above, with the fan facing the rear of
the board.


TESTING

Before thermal testing, we took some basic physical measurements.

Scythe Mugen-2:

Approximate Physical Measurements
Weight
740 g

850 g with fan and clips

870 g with fan, clips and topside mounting hardware
Fin thickness
0.31 mm
Fin spacing
1.89 mm
Vertical Clearance
48 mm (measured from the
motherboard PCB to the heatsink's bottom fin)
Horizontal Overhang
N/A (measured from the
edge of the heatsink to the top edge of our test motherboard's PCB)


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
Thermolab Baram
0.44 mm
2.52 mm
Prolimatech Megahalems
0.50 mm
2.00 mm
Xigmatek HDT-S1283
0.33 mm
1.96 mm
Scythe Mugen-2
0.31 mm
1.89 mm
Zerotherm Zen FZ120
0.37 mm
1.80 mm
Zalman CNPS10X Extreme
0.42 mm
1.50 mm
Thermalright Ultra-120
0.45 mm
1.42 mm

Testing was done according to our
unique heatsink testing methodology
, and the included fan was 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 120 fan (part of our standard testing methodology; used when
    possible with heatsinks that fit 120x25mm fans)
Nexus 120mm fan measurements
Voltage
Noise
RPM
12V
1100 RPM
9V
890 RPM
7V
720 RPM
5V
530 RPM

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.

TEST RESULTS

Stock Fan Testing

The stock fan is a PWM version of the SY1225SL12M from the acclaimed Slip Stream
series. We've been waiting a long time for Scythe to begin shipping their heatsinks
with PWM fans and it looks like they're finally starting to make the transition.




Stock Fan Specifications
Manufacturer Scythe Power Rating 2.16 W
Model SY1225SL12LM-P Airflow Rating 74.25 CFM
Bearing Type Sleeve RPM Rating 1200
Frame Size 120 x 120 x 25 mm Noise Rating 26.5 dBA
Hub Size 1.41" (35.9 mm) Header Type 4-pin PWM
Weight 110 grams Starting Voltage ~5V
The data in the green cells is provided by the manufacturer;
we measured the data cited in the blue cells

Like many other PWM fans, the fan speeds drop off very quickly when the voltage
is decreased. We typically test fans at 12V, 9V, 7V, and 5V, but this particular
fan becomes inaudible in our anechoic chamber at only 8V, so we adjusted our
levels appropriately. The fan speeds at 12V, 10V, 9V, and 8V differ by 200-300
RPM, offering a broad range for testing.

Fan Measurements
Voltage
Noise Level
Speed
12V
24 dBA
1340 RPM
10V
15 dBA
1020 RPM
9V
12 dBA
790 RPM
8V
11 dBA
500 RPM

Fan @ 12V: The fan produces mostly turbulent noise with a bit of a low-pitched
drone.

Fan @ 10V: At this level, the noise drops significantly from 24 [email protected]
to 15 [email protected] The acoustics are excellent with only a small amount of benign
turbulence.

Fan @ 9V: The fan sounds smooth as silk, with almost no bearing noise.
At 9V the noise characteristics rival that of the Nexus fan.

Fan @ 8V: Inaudible at one meter's distance.

Overall the fan is excellent just like previous Slip Streams. As far as stock
fans go, it is one of the best acoustically.

Cooling Results

Scythe Mugen-2 w/ stock fan
Fan Voltage
Temp
°C Rise
°C/W
12V
24 dBA
33°C
12
0.15
10V
15 dBA
35°C
14
0.18
9V
12 dBA
38°C
17
0.22
8V
11 dBA
45°C
24
0.31
Scythe Mugen-2 w/ reference 120mm fan
12V
16 dBA
36°C
15
0.19
9V
13 dBA
38°C
17
0.22
7V
12 dBA
40°C
19
0.24
5V
11 dBA
44°C
23
0.29
Load Temp: CPUBurn for ~10 mins.

°C Rise: Temperature rise above ambient (21°C) at load.

°C/W: based on the amount of heat dissipated by the CPU (measured
78W); lower is better.

The Scythe Mugen-2 performed very well, though suffered noticeably when the
fan speed was lowered to about 500 RPM. At 12V the CPU temperature was 12°C
above ambient, putting it in league with some of today's top heatsinks. The
temperature increased by 2°C at 10V but was accompanied by a sizable decrease
in noise — it is fairly quiet and unobtrusive at this level. At 9V, performance
degraded by an additional 3°C, and then another 7°C at 8V. The noise
the fan generates between 9V and 8V (800~500 RPM) is inaudible unless the environment is almost
completely silent.

The stock fan fared well against our reference Nexus fan, an admirable feat.
At similar noise levels, the two fans performed within 2°C of one another.
There is really no reason whatsoever to consider replacing the included fan.

Cooling Results - Two Fan Configuration

Resistance to airflow is higher the closer the fins are to one another, and
the wider heatsink, the further air has to travel to cool it effectively. The
Mugen-2 is wider than most at 100 mm wide and its fins are tightly-spaced, making
it a good candidate for two fans in a push-pull configuration.

Scythe Mugen-2 w/ reference 120mm fan
Fan Voltage
Temp
°C Rise
°C/W
12V
16 dBA
36°C
15
0.19
9V
13 dBA
38°C
17
0.22
7V
12 dBA
40°C
19
0.24
5V
11 dBA
44°C
23
0.29
Scythe Mugen-2 w/ Two reference 120mm fans
12V
20 dBA
32°C
11
0.14
9V
14~15 dBA
33°C
12
0.15
7V
12 dBA
34°C
13
0.17
5V
11 dBA
38°C
16
0.21
Load Temp: CPUBurn for ~10 mins.

°C Rise: Temperature rise above ambient (21°C) at load.

°C/W: based on the amount of heat dissipated by the CPU (measured
78W); lower is better.

With two of our reference fans in a push-pull configuration running at 12V,
the Mugen-2 exhibited only a minor 4°C improvement while increasing the
noise level by 4 dBA. As the fan speeds were lowered, the improvement increased
— two fans seem particularly fit for use at low fan speeds. At 9V, the
two fan setup was 1~2 dBA louder and 5°C cooler than one fan. At 7V and
5V, there was no measurable increase in noise using dual fans, and the CPU temperature
was improved by 6°C and 7°C, respectively.

Comparables

°C rise Comparison: The Best of the Best
Heatsink
Nexus 120mm 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 Mugen-2
15
17
19
23
Scythe Ninja 2
17
18
20
23
Thermolab Baram
18
20
22
25
Scythe Mugen-2 w/ Two reference 120mm fans
Scythe Mugen-2
11
n/a
13
16

The Mugen-2 managed a slight performance increase over the Ninja 2. It's a solid
heatsink, but used as delivered. it doesn't cool quite well enough to be called elite. As the fan speed is decreased, its relative position improves and it manages to get within 2-3°C of the Thermalright
HR-01+
, even though the Mugen's fin spacing is tighter than most of
the competition.

Where the Mugen-2 really shines is when a second quiet fan is added in a push-pull configuration. With both fans set to spin ~700rpm or lower, there is essentially no noise increase compared to just one fan, but the cooling performance moves up to levels never achieved in the past. A temperature rise of just 16°C at a noise level of 11 [email protected] is simply astonishing performance.

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 recording starts with 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

Scythe Mugen-2's bolt-thru mounting has been long
awaited by PC enthusiasts everywhere. We are not completely enthusiastic about how the bolt-through mounting was implemented — applying a screwdriver
to the back side of a motherboard is tedious and possibly dangerous.
Still, it is a much better alternative to plastic pushpins, especially for a large cooler
like the Mugen-2. Hard mounting ensures good contact between the cooler's base
and the CPU, and the heatspreader helps prevent the PCB from bending. It also ensures consistency from one installation to another; if the instructions are followed correctly, every user should achieve the same tight installation.

Shipping the
heatsink with a good quality PWM fan is an excellent move. Many users have motherboards
with fan controllers that only work with PWM fans, so for them this is a welcome
addition. Adding PWM functionality hasn't dulled the shine of the smooth-sounding
Slip Stream fan.

The Mugen-2's stock performance was slightly disappointing considering its substantial
cooling surface area. It flirted with elite silent cooler status but did not quite break through to the
upper echelon.

Where the Mugen-2 really shines is in a two-fan push-pull configuration.
The improvement in cooling was especially notable at
low fan speeds (read: in silent operation). With two of our reference Nexus fans running at 7V and 5V, the
CPU temperature improved by 6°C and 7°C respectively. Better still,
at 7V and below, the addition of the second reference fan did not result in
any measurable increase in noise level.

The Mugen-2 currently retails for US$35~$40, putting it in competition with direct-touch
heatpipe coolers from Xigmatek, Kingwin, and others. It may not perform quite
as well as the HDT-S1283,
but it does hold several key advantages: It has a more secure mounting
system, allows for "proper" orientation on AMD motherboards, and it ships with a superior fan. We're guessing that the stock PWM fan will soon be availble for separate purchase, and hopefully, priced similarly to the $10 for the original Slipstream series. The end price of $50 for silent cooling performance of this caliber would be an absolute steal.

Scythe Mugen-2
PROS



* Excellent single fan performance

* Superb dual fan performance

* Topnotch stock fan

* Secure installation method

* Fan faces the rear when mounted on most AMD boards
CONS



* Iinstallation a bit awkward
* Only one fan clip pair included

* Big




Our thanks to Scythe
for the Mugen-2 heatsink sample.





SPCR Editor's Choice Award

* * *

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* * *

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