Scythe Ashura CPU Cooler

Built in the same vein as the successful Mugen 4, the Scythe Ashura features a slimmer, asymmetrical body, and a larger 140mm Glide Stream fan.

September 9, 2013 by Lawrence Lee

Product	Scythe Ashura (SCASR-1000) CPU Cooler
Manufacturer	Scythe
Street Price	£40

For the past few years, Scythe’s CPU cooler lineup has been relatively pragmatic. They were known mainly for smaller niche offerings that didn’t cost an arm and a leg as well as for their great fans. Not since the days of the Scythe Ninja did they have a truly elite, attention-grabbing heatsink for enthusiasts to salivate over. The recently launched Mugen 4 was the first big step they’ve taken to compete with the big monster towers that have taken over the premium sector of the market. A revamped modern mounting system was essential to the Mugen 4’s excellent performance ands its reasonable Scythe-like price-tag really put it over the top. It earned the coveted SPCR’s Editor Choice badge with little debate.

The box.

Complementing the Mugen 4, is the Ashura. Its body has a sleeker, less rotund shape but it also has a wider face to accommodate a larger Glide Stream fan than the Mugen 4, a 140 mm model. Prolimatech debuted a similar type of heatsink three years ago with the Armageddon, but despite its superb performance, the single tower with single 140 mm fan genre never really took off. On a paper it seems like a good idea. The bigger, presumably more efficient fan cools a larger surface area, and the narrow body makes it easier for the air to blow all the way through. The fin-stack is also asymmetrical like the Thermalright HR-02, pushed off to one side to alleviate memory interference issues.

Package contents.

Inside the box, you’ll find the heatsink, a 140 mm fan, two sets of fan clips, a backplate and the necessary mounting hardware, and a paper assembly guide. We suspect a great deal of the Mugen 4’s excellence was due to the mounting system and the Ashura uses a very similar scheme.

Scythe Ashura (SCASR-1000): Specifications (from the product web page)
Model No:	SCASR-1000
Compatibility:	Intel®: Socket LGA2011 Socket T / LGA775 Socket LGA1155 Socket LGA1156 Socket LGA1366 AMD®: Socket AM2 Socket AM2+ Socket AM3 Socket AM3+ Socket FM1 Socket FM2
Dimensions:	145 x 65 x 161 mm / 5.71 x 2.56 x 6.34 inch
Weight:	750 g / 26.46 oz (excl. fan)
Accessory:	Mounting plate x2 (Intel), mounting plate x2 (AMD), mounting bar x1, screws for clips x4, mainboard screws x8, mounting screws x2, back plate spacer (Socket 775) x1, washers x4, wrench x1, fan clips x4, thermal grease, backplate, installation manual
Base Plate Material:	Nickel plated copper
Fan Model Name:	GlideStream 140 PWM (adapted Model)
Fan Model NO:	SY1425HB12M-P
Fan Dimensions:	140 x 140 x 25 mm / 5.51 x 5.51 x 0.98 inch
Noise Level:	13 – 30.7 dBA
Air Flow:	63 – 165 m³/h / 37.37 – 97.18 CFM
Fan Speed:	500 ± 300 rpm to 1300 rpm ± 10% (PWM-regulated)
Static Pressure:	1.47 ~ 10.0 Pa / 0.15 ~ 1.02 mmH²O

PHYSICAL DETAILS

The Scythe Ashura is composed of 50 aluminum fins friction-fit to six 6 mm thick copper heatpipes, which are in turn soldered to a nickel-plated copper base. According to our measurements, the heatsink’s dimensions are 16.3 x 14.5 x 6.5 cm and its weight is 770 grams (920 grams including the fan).

Compared to the Mugen 4, the Ashura’s layout looks more restrictive to airflow. The heatpipes are arranged in six rows rather than four and the fins are uniform rather than having strategically placed gaps to reduce impedance. The fins are also substantially thicker at 0.43 mm, though they are spaced at wider 1.93 mm intervals.

Measuring 65 mm across, the Ashura is only about three quarters as wide as the Mugen 4. It’s not a symmetrical heatsink either, with the base shifted over to one side.

Helping keep the Ashura together is a thick black plate on the top with the Scythe logo printed at the center.

The face of heatsink has slightly wavy contours. Its surface is inset to accommodate a square 140 mm fan.

The base looks like it has been ground down using a circular sander, leaving a hole at the center. The surface is convex — the point in the middle is actually the apex.

The stock fan is larger than the Mugen 4’s, a 1300 RPM PWM variant of Scythe’s Glide Stream 140 series.

BASE & INSTALLATION

The most critical aspect of installation is that the heatsink be securely
mounted. A firm mating results in good contact between the heatsink’s base and
the CPU heatspreader and more efficient heat conduction. Ideally it should
also be a simple procedure with the user having to handle as few pieces of
hardware as possible.

The mounting system is a big improvement from older Scythe models. It’s essentially the same as the Mugen 4 except they’ve ditched the plastic spacers in favor of taller stud nuts and plastic washers for insulation.

Mounting clips assembled.

The crossbar is secured to the mounting clips with two screws. A series of grooves over the base keeps the crossbar in place.

Fully mounted.

The uneven design keeps the fan clear of the memory slot. Clearance underneath the bottom fin is an ample 45 mm.

On the best heatsinks, very little thermal compound at the center is left behind. The Ashura’s mating is not quite as snug as the Mugen 4 and due to its unusual surface, the resulting pattern is circular.

TESTING

Before thermal testing, we took some basic physical measurements.

Approximate Physical Measurements
Weight	770 g (+150 g with stock fan)
Height	163 mm
Fin count	50
Fin thickness	0.43 mm
Fin spacing	1.97 mm
Vertical Clearance*	40 mm
* measured from motherboard PCB to bottom fin of heatsink

 

Large Heatsink Comparison: Average Fin Thickness & Spacing
Heatsink	Fin Thickness	Fin Spacing
SilverStone Heligon HE02	0.52 mm	3.30 mm
Thermalright HR-01 Plus	0.45 mm	3.15 mm
Thermalright HR-02 Macho	0.34 mm	3.12 mm
Scythe Ninja 3	0.39 mm	2.64 mm
Noctua NH-U12P	0.44 mm	2.63 mm
Noctua NH-C12P	0.47 mm	2.54 mm
Noctua NH-D14	0.43 mm	2.33 mm
Thermalright Archon SB-E	0.49 mm	2.33 mm
GELID Tranquillo Rev.2	0.40 mm	2.30 mm
Phanteks PH-TC12DX	0.39 mm	2.30 mm
GELID GX-7 Rev.2	0.31 mm	2.25 mm
Phanteks PH-TC14PE	0.40 mm	2.21 mm
be quiet! Dark Rock 2	0.38 mm	2.22 mm
Prolimatech Armageddon	0.51 mm	2.08 mm
Prolimatech Megahalems	0.50 mm	2.00 mm
Zalman CNPS10X Quiet	0.40 mm	2.00 mm
Scythe Ashura	0.43 mm	1.97 mm
Scythe Kabuto & Zipang 2	0.34 mm	1.94 mm
NZXT Havik 140	0.41 mm	1.91 mm
Scythe Mugen-2	0.31 mm	1.89 mm
SilverStone Tundra TD03 (radiator)	0.43 mm	1.86 mm
Swiftech Polaris 120	0.43 mm	1.85 mm
SilverStone Argon AR01	0.30 mm	1.85 mm
Thermalright Venomous X	0.53 mm	1.84 mm
Scythe Mugen 4	0.30 mm	1.82 mm
Noctua NH-C14	0.38 mm	1.79 mm
Enermax ETS-T40	0.40 mm	1.79 mm
Scythe Yasya	0.32 mm	1.78 mm
SilverStone Argon AR03	0.42 mm	1.72 mm
Cogage TRUE Spirit 1366	0.40 mm	1.70 mm
Arctic Cooling Freezer Xtreme Rev.2	0.30 mm	1.70 mm
Scythe Grand Kama Cross	0.38 mm	1.66 mm
Reeven Kelveros	0.47 mm	1.61 mm
Zalman CNPS9900 MAX	0.16 mm	1.59 mm
Thermalright Silver Arrow	0.32 mm	1.57 mm
Cooler Master Hyper 212 Plus	0.43 mm	1.54 mm
Thermalright Ultra-120 eXtreme Rev.C	0.56 mm	1.52 mm
Zalman CNPS10X Extreme	0.42 mm	1.50 mm

Testing on larger heatsinks are done on our
LGA1366 heatsink testing platform, while smaller coolers tackle our LGA1155 heatsink testing platform. A summary of the test system
and procedure follows.

Key Components in LGA1366 Heatsink Test Platform:

• Intel Core i7-965 Extreme
  Nehalem core, LGA1366, 3.2GHz, 45nm, 130W TDP.
• Asus
  P6X58D Premium ATX motherboard. X58 chipset.
• Asus
  EAH3450 Silent graphics card.
• Intel
  X25-M 80GB 2.5″ solid-state drive. Chosen for silence.
• 3GB QiMonda
  DDR3 memory. 3 x 1GB DDR3-1066 in triple channel.
• Seasonic X-650 SS-650KM
  650W ATX power supply. This PSU is semi-passively cooled. At the power levels
  of our test platform, its fan does not spin.
• Arctic Silver
  Lumière: Special fast-curing thermal interface material, designed
  specifically for test labs.
• Noctua 140 mm fan (used when possible with heatsinks that fit 140x25mm
  fans)
• Nexus 120 mm fan (used when possible with heatsinks that fit 120x25mm
  fans)
• Nexus 92 mm fan (used when possible with heatsinks that fit 92x25mm
  fans)

Key Components in LGA1155 Heatsink Test Platform:

• Intel Core i5-2400 Sandy Bridge core, LGA1155, 3.1 GHz, 45nm, 95W TDP, overclocked/volted to 3.6 GHz and 1.300V.
• Intel DP67BG ATX motherboard.
  P67 chipset.
• Asus
  EAH3450 Silent graphics card.
• Kingston
  SSDNow V 30GB 2.5″ solid-state drive. Chosen for silence.
• OCZ Platinum Extreme Low Voltage DDR3 memory. 2 x 2 GB, DDR3-1333 in dual channel.
• Seasonic X-400 SS-400FL
  400W ATX power supply. Passively cooled
• Arctic Silver
  Lumière: Special fast-curing thermal interface material, designed
  specifically for test labs.

The systems are silent under the test conditions, except for the CPU cooling
fan(s).

Normally, our reference fans are used whenever possible, the measured details
of which are shown below.

Reference Noctua 140mm fan Anechoic chamber measurements
Voltage	Speed	SPL@1m
12V	1250 RPM	28~29 dBA
9V	990 RPM	21 dBA
8V	880 RPM	18 dBA
7V	770 RPM	15~16 dBA
6V	660 RPM	13 dBA

 

Reference Nexus 120 mm fan Anechoic chamber measurements
Voltage	Speed	SPL@1m
12V	1080 RPM	16 dBA
9V	880 RPM	13 dBA
7V	720 RPM	12 dBA

 

Reference Nexus 92 mm fan Anechoic chamber measurements
Voltage	Speed	SPL@1m
12V	1470 RPM	17 dBA
9V	1280 RPM	14 dBA
7V	1010 RPM	12 dBA

Measurement and Analysis Tools

• Extech 380803 AC power analyzer / data logger for measuring AC system
  power.
• 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 sensors. The sensors are not calibrated,
  so results are not universally applicable. The hottest core reading is used.
• Prime95,
  used to stress the CPU heavily, generating more heat than most real applications.
  All instances are used to ensure full stress.
• CPU-Z,used to monitor the CPU speed to determine when overheating occurs.
• Thermometers to measure the air temperature around the test platform
  and near the intake of the heatsink fan.

Noise measurements are made with the fans powered from the lab’s 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 Prime95 to stress the processor, and the
graph function in SpeedFan was used to ensure that the load temperature is stable
for at least ten minutes. The temperature recorded is the highest single core
reading. The stock fans were tested at various voltages to represent a good
cross-section of airflow and noise performance.

The ambient conditions during testing were 10~11 dBA and 21~23°C.

STOCK FAN MEASUREMENTS

Specifications: Scythe Ashura Stock Fan
Manufacturer	Scythe	Power Rating	4.44 W
Model Number	SY1425HB12M-P	Airflow Rating	37.37 ~ 97.18 CFM
Bearing Type	Sleeve	Speed Rating	500 ~ 1,300 RPM
Frame Size	140 x 140 x 25 mm	Noise Rating	13 ~ 30.7 dBA
Hub Size	40 mm	Header Type	4-pin PWM
Blade Diameter	129 mm	Starting Voltage	3.0 ~ 3.5 V
Cable Length	30 cm	Weight	150 g
Corner Type	Open	Retail Availability	Yes
Additional notes:

The Glide Stream 140 is housed in an octagonal frame with square corners to accommodate 120 mm mounting holes. The hub is relatively small, the blades are skinny, and struts are curved in the opposite direction. This general design is carried over from the Slip Stream 120 series which offered excellent performance and acoustics. The version shipping with the Ashura is a PWM model with a speed of 1300 RPM. Like the Mugen 4, the Ashura’s fan lacks the anti-vibration padding that ships with retail versions of the Glide Stream line.

Stock Fan Measurements
Voltage	Speed	SPL@1m
12V	1440 RPM	34 dBA
9V	1110 RPM	26 dBA
8V	900 RPM	19 dBA
7.6V	710 RPM	14~15 dBA
Measuring mic positioned 1m at diagonal angle from the center of the heatsink. Ambient noise level: 10~11 dBA.

At full blast, the Glide Stream is a terror, pumping out a very high and turbulent-sounding 34 dBA@1m. More of the same is produced at 9V, though at 26 dBA@1m it’s more bearable. At 8V it becomes quiet and its profile is much smoother and broadband, though up close the bearing emits a slight off-kilter flutter. Between 8V and 7V, the speed drops off dramatically so we chose a voltage that produced about 700 RPM (7.6V) for our last test point. At this level the fan is barely audible from one meter’s distance but up close we did detect some bearing chatter. Overall, the sound of the fan is well above average, though it has some complexity that the Slip Stream series lacked.

The Glide Stream’s acoustic profile matches up very well to that of our Noctua 140 mm reference fan, one of the best-sounding models in our arsenal. With both fans running at 8V, the frequency distribution is eerily close with the exception of a few minor tonal peaks, most notably at about 350 and 1500 Hz, which contributes to the Glide Stream’s slightly higher noise level.

This is the screen capture of Fan Xpert 2’s auto-analysis of the Ashura stock fan on voltage control..

This is the screen capture of Fan Xpert 2’s auto-analysis of the Ashura stock fan on PWM control.

While the fan’s speed takes a noise dive below 8V on voltage control, its low starting voltage (< 3.5V) allows it to spin up at just 300 RPM. The fan is also easily silenced on PWM control, with a minimum speed of about 400 RPM.

TEST RESULTS

Test Results: Scythe Ashura
Fan Voltage	Single Fan		Dual Fan
	SPL@1m	Thermal Rise		SPL@1m
12V	34 dBA	38°C	N / A
9V	26 dBA	40°C
8V	19 dBA	42°C
7.6V	14~15 dBA	45°C
Reference 140 mm Fan
12V	29 dBA	40°C	38°C	31 dBA
9V	21~22 dBA	41°C	39°C	23~24 dBA
8V	18 dBA	43°C	40°C	20 dBA
7V	14~15 dBA	44°C	41°C	17 dBA
6V	12~13 dBA	46°C	43°C	13 dBA
Measuring mic positioned 1m at diagonal angle from the center of the heatsink. Ambient noise level: 10~11 dBA.

The Ashura was a strong performer, producing thermal rise above ambient of 45°C at 7.6V and 38°C at 12V. The stock fan’s results were on par with our reference Noctua 140 mm fan. While the Ashura is a skinnier heatsink than the Mugen 4, it actually benefited more running in dual fan configuration. When a second fan was added, the thermal rise dropped by 3°C at noise levels of 20 dBA@1m and below.

HEATSINK COMPARISON TABLES

°C Rise Comparison: CPU Coolers with Single Stock Fan
SPL (dBA@1m)	20	19	18	17	16	15	14	13	12	11
Thermalright HR-02 Macho		39				40	41		43
Scythe Mugen 4					40			42		45
Scythe Yasya			40					43
Cogage TRUE Spirit 1366				41		43			46
Zalman CNPS10X Quiet	40						42		47
Scythe Ashura		42				44
Cooler Master Hyper 212 Plus			41					44	54
Silverstone Argon AR03			43							48
Scythe Ninja 3			44					46
SilverStone Argon AR01			44							50

Out of the box, the Ashura is a solid performer, keeping pace with the CNPS10X Quiet and the Hyper 212 Plus. However, it lags well behind its more voluminous cousin, the Mugen 4.

°C Rise Comparison: CPU Coolers with Single 140 mm Reference Fan
Heatsink	Fan voltage / SPL @1m*
	9V (~20 dBA)	7V (~15 dBA)	6V (~12 dBA)
Thermalright Archon SB-E	37	40	42
Prolimatech Armageddon	39	42	45
Scythe Mugen 4	39	42	45
Thermalright HR-02 Macho	39	43	45
NZXT Havik 140	40	43	47
Scythe Ashura	41	44	46
Noctua NH-C14 (top mounted)	40	44	48
Noctua NH-C14	40	44	49
Thermalright Silver Arrow	39	45	49
Phanteks PH-TC14PE	42	45	48
SilverStone Heligon HE02	45	48	50
be quiet! Dark Rock 2	49	51	53
*Note: there are minor differences in measured SPL due to the variety of fan orientations and mounting methods offered by the compared coolers.

Paired with our reference 140 mm fan, trails the Mugen 4 by only a couple of degrees.

°C Rise Comparison: CPU Coolers with Dual 140 mm Reference Fans
Heatsink	Fan Voltage / SPL*
	8V (~19 dBA)	7V (~16 dBA)	6V (~13 dBA)
Prolimatech Genesis	36	37	39
Thermalright HR-02 Macho	36	37	40
Noctua NH-C14	37	39	41
Thermalright Silver Arrow	37	39	41
Noctua NH-D14	38	40	42
Scythe Mugen 4	39	40	42
Phanteks PH-TC14PE	39	41	43
NZXT Havik 140	39	40	43
Scythe Ashura	40	41	43
SilverStone Heligon HE02	43	44	46
*Note: there are minor differences in measured SPL due to the variety of fan orientations and mounting methods offered by the compared coolers.

The Mugen 4’s lead narrows to just 1°C with dual 140 mm reference fans but in this configuration, the bigger dual tower coolers dominate the chart.

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 5 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.

• Scythe Ashura with stock fan at 1m
  — 7.6V (14~15 dBA@1m)
  — 8V (19 dBA@1m)
  — 9V (26 dBA@1m)
  — 12V (34 dBA@1m)

• Scythe Ashura with reference 140mm fan at 1m
  — 6V (12~13 dBA@1m)
  — 7V (14~15 dBA@1m)
  — 8V (18 dBA@1m)
  — 9V (21~22 dBA@1m)
  — 12V (29 dBA@1m)

FINAL THOUGHTS

The Ashura is a fine addition to Scythe’s slowly growing stable of modern CPU coolers. The Glide Stream 140 fan isn’t an acoustical marvel like our Noctua NF-P14 reference fan, but it sounds pretty darn good and much better than almost any other out-of-the-box third party cooling solution on the market. The mounting system is also excellent, using the same basic style innovated by Prolimatech and Noctua that is now found on most high-end heatsinks. Compared to most other big towers being sold today, the Ashura has one other minor advantage. Its off-center design keeps it well away from the memory slots, allowing easy access and not interfering with DIMMs encumbered with large heatspreaders. This “feature” is only common on smaller, thinner heatsinks that generally don’t perform as well.

The Ashura has a mid-range price, currently selling in the UK for about £40 and 50€ in parts of Europe, about the same as the stouter cousin Mugen 4 and the Thermalright HR-02 Macho, both of which have a slight edge in performance. The HR-02 is an interesting comparable because it also has a similar asymmetrical design, while also boasting fantastic cooling with dual fans, and the ability to be used passively with lower power chips.The Ashura has a smooth-sounding Scythe fan though, which may give it the edge. This same advantage holds true against other budget coolers like the Zalman CNPS10X Quiet and Cooler Master Hyper 212 Plus which are roughly in the same league.

Our thanks to Scythe
for the Ashura CPU cooler sample.

Scythe Ashura
is Recommended by SPCR

* * *

SPCR Articles of Related Interest:

SilverStone Tundra TD03 Liquid CPU Cooler
Scythe Mugen 4 CPU Cooler: Scythe Strikes Back
SilverStone Argon AR02 CPU Cooler
NoFan CR-95C Copper Fanless CPU Cooler
SilverStone Argon AR01 & AR03 CPU Coolers
Noctua NH-U12S Slim Tower Heatsink

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