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Scythe pushes towards Infinity (renamed Mugen)

September 11, 2006 by Devon

Scythe Infinity / Mugen SCINF-1000

Socket 478 / 775 / K8 CPU Heatsink
Market Price

It's bigger! It's better! It's new and improved! It's yet another heatsink
from Scythe. Not that it's a bad thing. Scythe seems to release a new heatsink
every other month or so, and by and large, they're all pretty good.

The Infinity seems poised to pick up where the
left off. The Ninja made its name by being bigger than any other cooler
on the market, but the Infinity is bigger in every dimension and 150 grams heavier
to boot. Perhaps Scythe has something to prove — other manufacturers have
built similar heatsink behemoths and the Ninja is no longer the undisputed leader
it once was.

In any case, it will be not be a surprise if the Infinity outperforms the Ninja.
It has too many heatpipes and too much surface area not to do well. But there's
more to a heatsink than just performance. We've already shown that, with the
right system airflow, the Ninja
is good enough to cool just about any processor passively
. With the current
downward trend in CPU power consumption, the vast majority of users simply have
no need for anything better than the Ninja. And, although overclocking guarantees
that there will always be a market for the best performing heatsinks, other
factors, such as compatibility, ease of use, and price, will probably be more
relevant to most users.

This is one of the biggest heatsink boxes we've ever seen.

A complete set of mounting hardware, including support for Socket 478.

Scythe Infinity: Feature Highlights (from the
product web page
Feature & Brief Our Comment
IIFS - Infinity Interleave Fin Structure

Seeking the better way to efficiently dissipate the heat from total 5
heatpipes to Heatsink fins, this IIFS makes the quick & efficient
heat transfer ever!
Fin density is doubled around the heatpipes,
but still fairly open through most of the heatsink.
4 Fan Mounting Choice

Users can choose from 4 possible direction to mount the fan to get the
best performance out of Infinity!
Although the fan can be mounted on any
side, the heatsink is not symmetrical, and performance is likely to suffer
if the fan is installed on one of the less open faces.
Tool Free Easy Installation

Newly developed & "patent pending" mounting mechanism "VTMS
(Versatile Toll-Free Multiplatform System) allows user to install the
Infinity CPU Cooler without any tool and hassle. Infinity CPU Cooler is
compatible for socket 478/754/939/940/AM2 & LGA775. All in one solution
for your PC system.
One of the most convenient mounting systems we've seen. Also featured
on the Samurai Z and
Mine coolers.
Wide Range Cooling

Infinity CPU Cooler is optimized to get its performance from low-rpm to
high-rpm to meet the demand from silent users to heavy-core overclockers.
Perhaps this good performance under a
wide range of conditions is made possible by the interleaved fins mentioned
above? The included fan is low airflow.

Scythe Infinity: Specifications (from the
product web page
Model Name
Infinity CPU Cooler
Model Number
Scythe Co., Ltd. Japan
Combined Dimensions
125 x 116 x 160 mm
960 g
Fan Dimensions
120 x 120 x 25 mm
Noise Level
23.5 dBA
Air Flow
46.5 CFM
1,200 RPM (±10%)
Intel® LGA775 (SocketT) Processors

-Intel® Core™2 Extreme processor (Conroe)

-Intel® Core™2 Duo processor (Conroe)

-Intel® Pentium® Processor Extreme Edition

-Intel® Pentium® D Processor

-Intel® Pentium® 4 Processor Extreme Edition supporting Hyper-Threading

-Intel® Pentium® 4 Processor supporting Hyper-threading Technology

-Intel® Celeron® D Processor

Intel® Socket478 Processors

-Intel® Pentium® 4 Processor Extreme Edition supporting Hyper-Threading

-Intel® Pentium® 4 Processor supporting Hyper-threading Technology

-Intel® Pentium® 4 Processor

-Intel® Celeron® D Processor

-Intel® Celeron® Processor

AMD Socket AM2 Processors

-AMD Athlon™ 64 Processor

-AMD Athlon™ 64 FX Processor

-AMD Athlon™ 64 X2 Dual-Core Processor

-AMD Sempron™ Processor

AMD Socket940 Processors

-Dual-Core AMD Opteron™ Processor

-AMD Opteron™ Processor

-AMD Athlon™ 64 FX Processor

AMD Socket939 Processors

-Dual-Core AMD Opteron™ Processor

-AMD Opteron™ Processor

-AMD Athlon™ 64 Processor

-AMD Athlon™ 64 FX Processor

-AMD Athlon™ 64 X2 Dual-Core Processor

AMD Socket754 Processors

-AMD Athlon™ 64 Processor

-AMD Sempron™ Processor


The stack of aluminum fins that makes up the bulk of the Infinity
is enormous. At 160 mm tall, it may have trouble fitting into some narrower
cases, and its wide dimensions may also cause it to intrude into the space for
the power supply on some motherboards. Fortunately, the stack of fins does not
start right at the bottom; there should be enough clearance for motherboard
components, including RAM.

Scythe is aware of the potential for compatibility problems,
as they have embarked on an ambitious project to verify compatibility with current
motherboards from Abit, Asus, EPoX, and MSI. At the time of writing, data
is only available for Abit boards
, but the level of detail will be quite
impressive if the project is finished. Some boards even have photos showing
how it was installed. Scythe has also taken pictures of the
Infinity in an Antec P180 case
in an effort to show that the height of the
heatsink is not a problem — at least in this particular configuration.

A heatsink this big doesn't mess around.

Unlike the Ninja, the Infinity is not designed for passive use. It does
not have the symmetrical shape or the holes in the fins that allowed the Ninja
to take good advantage of system airflow. Although a fan can be mounted on any of its
four sides, the optimal air path clearly requires the fan to be mounted on one
of the wider sides. In this configuration, the air should flow parallel to two
lines of heatpipes that dissipate heat evenly through the full thickness of
the heatsink.

For the most part, fin spacing is wide enough that even very slow fans should
not have trouble forcing air through it. The fin density doubles up around the
heatpipes, which should increase the cooling potential with faster fans. The
two different fin densities should bear out Scythe's claim that the Infinity
can do well with either low or high airflow fans.

The double fin density is achieved by using three different sets of fins that
overlap around the heatpipes. One set spans the area between the two lines of
heatsinks, while another set hangs off each edge.

If you look closely, you can see three sets of fins in the tower.

Airflow is much more restricted from this direction.

Fins are interleaved around the heatpipes.

The Infinity uses five U-shaped heatpipes that extend 10 pipe lengths upwards from a thin copper
base. These should carry a lot of heat — the Ninja is the only heatsink
we've seen with more (12).

Sandwiched between the heatpipes and the bottom fins is a small secondary heatsink
that resembles the one found on the bottom of the
Samurai Z
. The Infinity lacks the cross-cuts through that allow the air
to escape sideways in the Samurai Z, but they are otherwise identical.


The fan's model number identifies it as an Adda model — the same one found
in several of Scythe's other products, including the Ninja Plus. Decoding the
model number reveals that the fan is classified as "Ultra Low" speed,
and has a sleeve bearing. Scythe heatsinks generally come with quiet fans,
and this one should be no exception.

A low speed model that appears to be sourced from Adda.

As mentioned, the fan can be attached to any of the heatsink's four sides,
but it looks goofy on the narrow ends. The low speed fan is
unlikely to do well in this configuration; not only does it have to contend
with the double fin density across the whole width of the heatsink, but the
heatpipes themselves block a substantial portion of the airflow.

The fan is mounted using two wire clips that are identical to the clips that
come with the Ninja. The clips can be quite tight, and several Ninja users complained
that they were difficult to install. This goes double when installing the fan
on the ends of the heatsink as the narrower sides put the clips under even greater

Just because it's possible to mount the fan this way doesn't make it a good

The is how the fan should be mounted for optimal cooling.


The copper base is polished flat and smooth, and is thinner than most bases.
It is also slightly wider, as it must be to transfer heat to all five heatpipes.

The base is mirror smooth.

The Infinity uses the same universal mounting system as the Samurai Z and the
Mine, both of which impressed us with their ease of use and the fact that they
require no tools. All three of the common CPU sockets are supported: Socket
478, Socket 775, and AMD's K8 sockets, including AM2. Each mounting
system comes with its own set of clips, which themselves clip onto the heatsink
as illustrated below.

The mounting system uses the stock retention brackets for Socket 478 and K8
systems, neither of which is well suited to supporting nearly a kilogram of
metal. The K8 mounting system in particular seems very fragile, as the heatsink
is only held on by two thin plastic nubs. We would not recommend moving any
system with the Infinity installed. Although not as simple to use, a backplate-based
mounting system might be more appropriate for a heatsink of this size.

The clip for Socket 478...

...attaches to the heatsink as shown here.

Unfortunately, the universal mounting system does not allow the heatsink orientation
to be chosen. Socket 775 systems avoid this issue thanks to the square layout
of the mounting holes, but other systems may end up with the heatsink facing
the wrong direction. K8 boards that can mount the Infinity correctly should
have mounting nubs pointing towards the backplate.

Socket 478 boards may face a problem no matter which orientation the Infinity
would be installed. Most boards that support Socket 478 locate the CPU very
close to the top edge of the board, which means that, if the heatsink it oriented
so that air is blown out the back, the side fins are likely to hang over the
top edge of the board — the space typically occupied by the power supply.
On the other hand, boards that do not have this problem will inevitably require
the airflow to be vertical, which is less than ideal for low noise cooling.
In addition, Socket 478 was not designed with as much clearance around the CPU
socket as more recent systems, so the Infinity's large size may be an issue.
The photos below show how tight a fit it was in our test system.

The fan just barely clears the RAM on our test system.

On the other side, the heatpipes touch the capacitors beside of the retention


Test Platform

  • Intel
    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
    & 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-4000, 512 MB
  • Seagate Barracuda IV 40G 1-platter drive (in Smart
  • Seasonic Super Tornado 300
    (Rev. A1)
  • Arctic Silver
    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 4.22
    software to show CPU temperature
  • A custom-built variable DC power supply that allows us to dial in exactly
    what voltage is powering the fan
  • Neiko Digital Laser Tachometer to measure fan RPM
  • A digital caliper micrometer to measure fin thickness
  • B&K model 1613 sound level meter

Noise measurements were made with the fan powered from the lab variable DC
power supply while the rest of the system was off to ensure that system noise
did not skew the measurements.

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. Every fan was tested at four voltages: 5V,
7V, 9V, and 12V, representing a full cross-section of the fan's airflow and
noise performance.

The ambient conditions during testing were 16 dBA and 24°C.


Fan Comparison: Scythe Infinity vs. Nexus 120mm
Stock Fan
Nexus 120mm






















The fan included with the Infinity is one of the quietest stock fans we've
ever seen, and is similar in many respects to our reference Nexus 120mm fan.
The two fans spin at almost exactly the same speed, with the Infinity's fan
just slightly faster at full voltage. They move similar amounts of air, and
they performed identically on the test bench.

From a noise perspective, the Nexus was clearly superior. It sounded
smoother and softer, and was audibly quieter at a given voltage. The difference
was most audible when the fans were spinning at close to full voltage. Both
fans were inaudible from one meter at 5V and just barely audible at 7V.

Unfortunately, our sample of the stock fan appeared to be damaged,
and developed an audible clicking when held at certain angles. At lower voltages,
the clicking turned into a chuffing, but we do not believe that the noise was

Two thermal tests were run with each fan: One with the fan installed
on the wide side and one on the narrow. As mentioned, the two fans performed
identically in both tests.

Scythe Infinity with stock or Nexus
120 fan: Narrow side
Fan Voltage
°C Rise




Scythe Infinity with stock or Nexus
120 fan: Wide




Load Temp: CPUBurn for ~20 mins.

°C Rise: Temperature rise above ambient (24°C) at load.

°C/W MP / TDP: Temperature rise over ambient per Watt of CPU heat,
based on CPU's Maximum Power (79W) or Thermal Design Power (69W) rating
(lower °C/W is better)

Noise: SPL measured in [email protected] distance with high accuracy B &

Fan @ 12V: The stock fan was quiet at full speed. This is a highly unusual
comment for SPCR; the Infinity is one of a very small selection of heatsinks
we would consider acceptable at full speed. That's not to say things can't be
improved — it wasn't inaudible — but it was quieter than any other
heatsink/fan we can think of.

The noise consisted of a smooth midrange hum that was quite easy to tune out.
Compared to the Nexus fan, the stock fan sounded more tonal but produced
less turbulence noise.

Performance was very good no matter how the fan was mounted (there was very
little difference), but not record-breaking.
At this level of airflow, the Ninja still outperformed the Infinity by about
four degrees. However, keep in mind that, even at full speed, the stock fan
still qualifies as a low airflow fan. At higher airflow (and noise) levels,
we would expect the Infinity to do better.

Fan @ 9V: At this level, the stock fan was roughly as loud as the Nexus
at full speed, although the Nexus still managed to sound a bit softer. As before,
the noise was a tonal hum with little turbulence It is a challenge to build
a system that is quieter than the fan at this level — for many people,
there may be no acoustic benefit to turning down the fan below this point.

Performance remained very good, although there was now a noticeable gap between
the two different mountings. With the fan mounted on the wide side, the performance
drop from 12V was marginal, but this was not true of the other configuration.

Fan @ 7V: At this level, the Nexus fan was inaudible from one meter,
and the stock fan very nearly so. In either case, there would be little point
in reducing the fan speed any more. In a system with other sources of noise,
the difference would not be heard. Only a very low frequency hum let us know
that the stock fan was spinning, and that was audible only when closely listened

The Infinity continued to show very good performance with low airflow, losing
only three degrees off the performance at full speed. With the fan installed
on the narrow end, this gap was five degrees — still an impressive result
even if not quite a showcase of what the Infinity is really capable of.

Interestingly, the performance gap between the Ninja and the Infinity was smaller
at 7V than it was at full speed. With only 0.03 °C/W separating the two
heatsinks, it's too close to call, especially considering that the Ninja
had the advantage of being tested at a lower ambient temperature.

Fan @ 5V: Both fans were inaudible from one meter at this level. If
you want to guarantee that you won't hear the Infinity, running the fan at five
volts is a good way to do it.

And, unlike most heatsinks, the Infinity should be able to handle this little
airflow unless your processor is especially hot. Our test processor was well
beneath its throttle point, and would likely remain so even in the thermal constraints
of an actual system.

One drawback: Performance with the fan mounted on the narrow end suffered significantly
at this level. Even so, with a reasonably cool processor it might still be good
enough, especially with the help of a little system airflow. We would not recommend
trying to cool a hot processor in this way though.


The obvious competitor for the Infinity is Scythe's own Ninja. Our test of
the Ninja used a Nexus 120mm fan, which, as we showed above performs almost
identically to the stock fan. Both the Infinity and the Ninja Plus come with
the same stock fan, so this comparison can be used to judge between the two
heatsinks in their stock form.

Comparison: Scythe Infinity vs. Scythe Ninja
Fan Voltage
Scythe Infinity
Scythe Ninja
°C Rise
°C Rise

While both heatsinks are clearly excellent performers, a side by side comparison
leaves no doubt that our Ninja sample is the better of the two — at least with
low airflow. The difference is not great, but it is there.

Nevertheless, we should stress that these results apply specifically to low
airflow situations that are of interest to silencers. It seems quite likely
that the Infinity could reverse the standings if the two were tested with a
noisy, high speed fan, as it would be helped by its larger size and the closely
spaced fins around the heatpipes. [Editor's Note: It's also possible that our sample of the Ninja is unusually good. Recently, we've learned that sample variiance in heatpipe production is high enough to affect the actual cooling performance of many heatsinks.]

Keep in mind that on our hotter 775 test platform, the Ninja was recently edged by Thermalright's Ultra 120. This suggests that the Infinity would be surpassed in performance by the Ultra 120 as well.


Scythe Infinity: 5V-7V-9V-12V, 5s Ambient between
: One Meter,
One Foot

Note: Our sample of the Infinity appeared to
be damaged, and developed a clicking under certain conditions. This clicking
can be heard at the end of the one foot recording.


Arctic Cooling Alpine 64: 5V-7V-9V-12V, 5s Ambient
between levels
: One
, One Foot

Scythe Mine w/ stock fan: 5V-7V-9V-12V, 5s Ambient
between levels
: One
, One Foot

Nexus 120mm fan: 5V-7V-9V-12V, 5s Ambient between
: One
, One Foot


These recordings were made
with a high resolution, studio quality, digital recording system and are
intended to represent a quick snapshot of what we heard during the review.
Two recordings of each noise level were made, one from a distance of one
, and another from one foot away.

The one meter recording is
intended to give you an idea of how the subject of this review sound 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. For best results, set your volume control so that the ambient
noise is just barely audible. 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 one foot recording is
designed to bring out the fine details of the noise. Use this recording
with caution! Although more detailed, it may not represent how the subject
sounds in actual use. It is best to listen to this recording after you
have listened to the one meter recording.

More details about how we
make these recordings can be found in our short article: Audio
Recording Methods Revised


The Infinity is big enough to cool just about anything, even with low airflow.
Even if it cannot beat our Ninja or Thermalright Ultra-120 samples, it's still a very good

The Infinity's biggest advantage over the Ninja is its mounting system, which
is easy to use, doesn't require any tools, and doesn't require removing the
motherboard. It also supports AM2 — which the Ninja does not... yet. On
the other hand, the Ninja has several advantages of its own: It's smaller, lighter,
and is therefore likely to be more widely compatible. And, despite being difficult
to use, its mounting system seems more secure.

In the end, it's best just to evaluate the Infinity on its own merits. The
Infinity is a very quiet, well-performing heatsink that is easy to use. It should
be able to cool just about any processor with a minimum of noise. So long as
compatibility issues can be avoided, it is a solid choice for a quiet system.


* Excellent low-airflow performance

* Very quiet fan

* Easy, tool-free installation

* Performs well enough to use fan at 5V

* Performs well even with fan mounted on "bad" side

* Large enough to cause compatibility issues

* Very heavy

* Mounting system may not be secure enough for weight

* Heatsink orientation inflexible

* Wire fan clips are difficult to use

Much thanks to Scythe
for the Infinity sample.

* * *

Articles of Related Interest

Recommended Heatsinks

Scythe Samurai Z CPU Heatsink
/ Fan

Scythe SCNJ-1000
Ninja Heatsink

Scythe "Summit"
Mine Heatsink / Fan

Thermalright Gets Back
on Top with the Ultra-120

* *

on this article in our Forums



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