The Scythe Grand Kama Cross is a down-blowing CPU cooler featuring a large 140mm SlipStream fan, 4 copper heatpipes twisted to form a “X” formation, and an relatively small stack of aluminum fins. Does it have what it takes to compete with the big tower heatsinks?
May 24, 2010 by Lawrence Lee
|
Product
|
Scythe Grand Kama Cross SCKC-2000 CPU Cooler |
|
Manufacturer
|
Scythe Co., Ltd. |
|
Street Price
|
US$40~$50 |
As computer microprocessors continue to ramp up in speed and power consumption,
modern motherboard components that deal with power management are subject to
an ever increasing amount of stress. Current high-end motherboards ship with
high quality components and heatsinks for the voltage regulators as manufacturers
expect enthusiasts to dish out even more stress through overclocking. It is
ironic that these same users typically use large side-blowing tower CPU heatsinks,
reducing the helpful top-down airflow most stock cooler units provide over the
components surrounding the CPU socket.
For those concerned about this issue, down-blowing heatsinks are better, though
they generally do not cool the processor as effectively, partly because they
do not blow exhaust out toward the back of the system. An ideal top-down cooler
would provide improved socket cooling without sacrificing much in the way of
CPU cooling proficiency.
Enter the Scythe Grand Kama Cross, a larger version of the Kama Cross, a modestly
sized cooler with only 3 copper heatpipes and a 100 mm fan. The Grand version
is much larger, featuring four heatpipes with airflow provided by a 140 mm Slip
Stream fan. It is unusual looking with the heatpipes curving inward so that
the ends cross each other in a “X” formation. The aluminum fins around
the heatpipes are tightly spaced, angled to direct airflow around the socket,
and surprisingly short, particularly at the ends. The total area of the fins
is lower than usual for a heatsink of this size.
|
|
|
|
While Scythe has introduced hard mounting systems for some of their heatsinks,
the Grand Kama Cross, despite weighing 750 grams, ships with S478, AMD, and
LGA775/1156/1366 mounting frames that utilize stock mounting mechanisms. On
the Intel side, not only do you have to deal with push-pins, but for LGA1156,
the pins have to be slid halfway between the LGA775 and 1366 positions. There
is nothing to lock the push-pin in place, which can result in a mounting that
is off-center. The only good thing about these frames is they can be rotated,
which is useful for the Grand Kama Cross since one side is much wider than the
other. If the heatpipe ends are arrayed vertically, it could interfere with
the power supply in many ATX tower cases.
|
|
|
Scythe Grand Kama Cross: Key Features
(from the product web page) |
|
| Feature & Brief | Our Comment |
| Top Mount Fan By pointing the airflow of the fan towards the motherboard, Chipsets and MOS-FETs on VR modules can be cooled simultaneously. |
Blowing down on the motherboard has its advantages, but this usually results in poorer CPU cooling compared to heatsinks that blow out the side. |
| Slip Stream 140 mm PWM Fan By applying the new SLIP STREAM140 fan, wider area of components on the motherboard can be cooled compared to 120mm fans while keeping low noise and high cooling ability for the CPU. |
120mm Slip Streams perform well and have excellent acoustics. The Grand Kama Cross uses a large 140 mm PWM model. |
| 4-Way Mounting 4-Way (direction) mounting is available. This allows you to configure the optimized airflow direction inside your chassis without and restrictions. |
Like many Scythe coolers, the mounting frame is secured from the bottom with a square hole configuration, allowing it to be freely rotated. |
|
Scythe Grand Kama Cross: Specifications
(from the product web page) |
|
| Model Name | Grand Kama Cross CPU Cooler |
| Model No | SCKC-2000 |
| Compatibility | Intel®: Socket 478 Socket T / LGA775 Socket LGA1156 Socket LGA1366 AMD®: |
| Dimensions | 177 x 140 x 137 mm / 6.97 x 5.51 x 5.39 in |
| Fan Dimensions | 140 x 140 x 25 mm / 5.51 x 5.51 x 0.98 in |
| Noise Level | 9.6 ~ 24.7 dBA |
| Air Flow | 27.2 ~ 69.93 CFM |
| Fan Speed | 500 ~ 1,300 rpm (± 10%) |
| Weight | 750 g (26.46 oz) |
| Material of Base Plate | Nickel-plated copper |
PHYSICAL DETAILS
The Grand Kama Cross is composed of 4 copper heatpipes, and 72
short aluminum fins. It measures 177 x 140 x 137 mm (W x D x H) and weighs about
610 grams, 750 grams with the stock fan and bolts.
|
|
|
|
|
|
|
|
|
|
|
|
TESTING
Before thermal testing, we took some basic physical measurements.
|
Approximate Physical Measurements
|
|
|
Weight
|
610 g 750 g with fan and bolts |
| Fin count | 72 |
|
Fin thickness
|
0.38 mm |
|
Fin spacing
|
1.66 mm |
|
Vertical Clearance
|
51 mm (from the motherboard PCB to the bottom fin) |
|
Horizontal Overhang (+/-)
|
–18 mm (far edge of the heatsink to the top edge of the motherboard 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
|
|
Noctua NH-C12P
|
0.47 mm
|
2.54 mm
|
|
Thermolab Baram
|
0.44 mm
|
2.52 mm
|
|
Noctua NH-D14
|
0.43 mm
|
2.33 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
|
|
Xigmatek HDT-S1283
|
0.33 mm
|
1.96 mm
|
|
Scythe Kabuto & Zipang 2
|
0.34 mm
|
1.94 mm
|
|
Scythe Mugen-2
|
0.31 mm
|
1.89 mm
|
|
Cooler Master V8
|
0.30 mm
|
~1.85 mm
|
|
ZEROtherm Nirvana
|
0.43 mm
|
1.82 mm
|
|
ZEROtherm Zen
|
0.37 mm
|
1.80 mm
|
|
Titan Fenrir
|
0.36 mm
|
1.78 mm
|
|
Cogage TRUE Spirit 1366
|
0.40 mm
|
1.70 mm
|
|
Scythe Grand Kama Cross
|
0.38 mm
|
1.66 mm
|
|
Cooler Master Hyper 212 Plus
|
0.43 mm
|
1.54 mm
|
|
Zalman CNPS10X Extreme
|
0.42 mm
|
1.50 mm
|
|
Thermalright Ultra-120
|
0.45 mm
|
1.42 mm
|
Testing was done on our
new i7-1366 heatsink testing platform. A summary of the test system
and procedure follows.
Key Components in 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. - Nexus 120 fan (part of our standard testing methodology; used when
possible with heatsinks that fit 120x25mm fans)
The system is silent under the test conditions, except for the CPU cooling
fan(s).
Normally, our reference fan is used whenever possible, the measured details
of which are shown below.
|
Reference Nexus 120mm fan
Anechoic chamber measurements |
||
|
Voltage
|
SPL@1m
|
Speed
|
|
12V
|
16 dBA
|
1100 RPM
|
|
9V
|
13 dBA
|
890 RPM
|
|
7V
|
12 dBA
|
720 RPM
|
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.
8 instances are used to ensure that all 4 cores (with Hyper-threading) are
stressed. - 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.
TEST RESULTS
Stock Fan
The 140 mm PWM Slip Stream is a 9-blade fan with a curved, but not quite round
|
Stock Fan Specifications
|
|||
|
Manufacturer
|
Power Rating
|
2.64 W | |
|
Model Number
|
SM1425SL12LM-P
|
Airflow Rating
|
69.93 CFM |
|
Bearing Type
|
Sleeve
|
RPM Rating
|
1300 RPM |
|
Corners
|
Open
|
Noise Rating
|
24.7 dBA |
|
Frame Size
|
120 x 120 x 25 mm
|
Header Type
|
4-pin PWM |
|
Fan Blade Diameter
|
128 mm |
Starting Voltage
|
~5.4 V |
|
Hub Size
|
40 mm |
Weight
|
140 g |
|
Data in green cells provided by the manufacturer
or observed; data in the blue cells were measured. |
|||
housing, 120 mm fan holes, and a surprisingly small hub.
|
Stock Fan Measurements
|
||
|
Voltage
|
Speed
|
SPL @1m
|
|
12V
|
1310 RPM
|
28 dBA
|
|
10V
|
1090 RPM
|
21 dBA
|
|
9V
|
970 RPM
|
17 dBA
|
|
8V
|
820 RPM
|
14 dBA
|
|
7V
|
680 RPM
|
11~12 dBA
|
|
Measuring mic positioned 1m at diagonal angle from
the intake side of the fan. Ambient noise level: 11 dBA. |
||
The stock fan was previously tested when we reviewed the Prolimatech
Armageddon, and the noise level was very similar with the exception
of a 2 dBA increase at 12V which may have been caused by the metal frame to
which the fan is mounted. Thankfully, this is not a serious issue since we consider
both 26 dBA and 28 dBA too loud for serious consideration in a quiet PC.
The fan exhibits some minor bearing chatter, and is a little whiny at full
speed, but other than that, its acoustics are excellent throughout its range
like other members of the Slip Stream family. The fan is really only too loud
at 12V. At 10V, the measured noise level is high at 21 dBA, but all you really
hear is turbulence. It undervolts well, becoming inaudible at around 7V.
|
|
Cooling Results
|
Scythe Grand Kama Cross w/ stock 140 mm fan
|
|||
|---|---|---|---|
|
Fan Voltage
|
SPL@1m
|
Temp
|
°C Rise
|
|
12V
|
28 dBA
|
59°C
|
38
|
|
10V
|
21 dBA
|
61°C
|
40
|
|
9V
|
17 dBA
|
62°C
|
41
|
|
8V
|
14 dBA
|
65°C
|
44
|
|
7V
|
11~12 dBA
|
70°C
|
49
|
|
Scythe Grand Kama Cross w/ ref. 120 mm fan
|
|||
|
12V
|
16 dBA
|
66°C
|
45
|
|
9V
|
13 dBA
|
73°C
|
52
|
|
7V
|
12 dBA
|
78°C
|
57
|
| Load Temp: Prime95 for ~10 mins. °C Rise: Temperature rise above ambient (21°C) at load. |
|||
The Grand Kama Cross performed admirably considering that it is a top-down
cooler. With the stock fan at fairly quiet 17 and 14 dBA levels, the thermal
rise above ambient was only 41°C and 44°C, respectively. At 11-12 dBA
the fan becomes almost inaudible, and the temperature increased by an additional
5°C. This would put the in-case temperature of the CPU at ~80°C or higher,
which is probably too high for most users’ comfort… but it may be a perfect
acceptable setting if you know you will rarely push the CPU as hard was we do
in our testing (100% load on all cores for >20 minutes continuously.)
Our Nexus 120 mm reference fan is apparently too small to be as effective as
the stock 140mm fan, allowing the CPU to get 4°C hotter at 12V/16 dBA than
the stock fan at 9V/17 dBA. As the reference fan’s speed was slowed, the difference
became more apparent. With both fans at 7V, the stock fan was slightly quieter
and a very significant 8°C cooler. It’s clear that the large stock fan is
essential to the Grand Kama Cross’ success.
Comparison Chart
|
°C rise Comparison
|
|||
|
Heatsink
|
Nexus 120mm fan voltage /
SPL @1m |
||
|
12V
|
9V
|
7V
|
|
|
16 dBA
|
13 dBA
|
12 dBA
|
|
|
Prolimatech Megahalems
|
38
|
41
|
44
|
|
Noctua NH-D14
|
38
|
42
|
45
|
|
Noctua NH-U12P
|
39
|
42
|
44
|
|
Scythe Mugen-2
|
39
|
42
|
45
|
|
Cogage TRUE Spirit 1366
|
40
|
42
|
45
|
|
Prolimatech Armageddon
|
40
|
42
|
46
|
|
Zalman CNPS10X Quiet
|
40
|
43
|
46
|
|
Thermalright U120 eXtreme
|
40
|
43
|
48
|
|
Cooler Master Hyper 212 Plus
|
41
|
44
|
48
|
|
Scythe Grand Kama Cross
(Stock 140 mm fan) |
17 dBA (9V)
|
14 dBA (8V)
|
11~12 dBA (7V)
|
|
41
|
44
|
49
|
|
|
Thermalright U120
|
42
|
45
|
49
|
|
Titan Fenrir
|
43
|
46
|
50
|
|
Noctua NH-C12P
|
43
|
47
|
51
|
|
Zalman CNPS10X Extreme
|
43
|
47
|
53
|
|
Zalman CNPS10X Flex
|
45
|
50
|
54
|
|
Cooler Master V8
|
46
|
50
|
54
|
|
Scythe Grand Kama Cross
|
45
|
52
|
57
|
|
Scythe Kabuto
|
51
|
53
|
60
|
The large, efficient stock fan of the Grand Kama Cross propels it past the
Noctua NH-C12P as
our best top-down cooler, and challenges some of the better tower heatsinks.
When paired with our reference 120 mm fan, it drops far down in the chart, but
still dishes out a severe beat-down to the Scythe
Kabuto.
It may not be as effective when it comes to cooling the components around
the socket though, as the height of the heatsink without the fan is 112 mm,
compared to 91 mm for the Noctua NH-C12P. The Noctua’s fan, though smaller,
is closer to the PCB by almost an inch, and the closer proximity may have an
impact on cooling effectiveness of the motherboard components.
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.
The 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 5~10 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.
- Scythe
140 mm Slip Stream fan at 1m
— 7V (11~12 dBA@1m)
— 8V (14 dBA@1m)
— 9 (17 dBA@1m)
— 10V (21 dBA@1m)
— 12V (28 dBA@1m)
- Nexus
120mm Real Silent Case fan at 1m
— 5V (11 dBA@1m)
— 7V (12 dBA@1m)
— 9V (13 dBA@1m)
— 12V (16 dBA@1m)
FINAL THOUGHTS
We were skeptical at first about how well the Scythe Grand Kama Cross would
perform due to its relatively modest surface area and tightly spaced fins—
this combination typically spells lower performance for quiet CPU cooling. These
fears proved to be unfounded as the GKC performed very well on our testbed,
even rivalling some very successful tower coolers. The included 140 mm Slip
Stream fan is probably the best stock fan that ships with any heatsink, both
in terms of performance and acoustics. Our only criticism is the traditional
mounting methods used for this big heatsink. A metal backplate with bolts is
strongly recommended for a cooler of its size and weight. We wish Scythe would
retool the mounting systems for all its big coolers.
The Grand Kama Cross delivered the best CPU cooling for a down-blowing heatsink
on our LGA1366 test bed to date, but the Noctua
NH-C12P may be the better top-down cooler overall. Though more expensive
and equipped with an inferior fan, the Noctua heatsink mounting system is immeasurably
better and its shorter stature puts its fan closer to the socket and surrounding
components by almost an inch. Of course, the Noctua is also most costly. If
you care only about CPU temperature, the Grand Kama Cross is the better choice
of the two, but budget tower coolers like the Cogage
TRUE Spirit or Cooler Master
Hyper 212 Plus are also viable alternatives.
|
Scythe Grand Kama Cross
|
|
| PROS
* Excellent stock fan |
CONS
* Traditional mounting schemes |
Our thanks to Scythe
Co., Ltd. and for the Grand Kama Cross heatsink sample.
* * *
Articles of Related Interest
Titan Fenrir & Coolermaster Hyper 212 Plus: Direct Touch Revisited
Corsair Hydro H50 CPU Water Cooler
Prolimatech Armageddon & Coolermaster
V8 CPU Coolers
Cogage TRUE Spirit
& Zalman CNPS10X Quiet CPU Coolers
SPCR’s 2010 CPU Heatsink
Test Platform [UPDATED: 10 April 2010]
Zalman CNPS10X Flex CPU Cooler
* * *
