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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.
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