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TESTING
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-3700, 512 MB
- Seagate Barracuda IV 40G 1-platter drive (in Smart
Drive from Silicon
Acoustics)
- Seasonic
Super Tornado 300 (Rev. A1)
- Arctic Silver
Ceramique Thermal Compound
- Two-level plywood platform with foam damping feet. Motherboard on
top; most other components below. Eases heatsink changes and setup.
Measurement & Analysis Tools
The ambient temperature in the test lab was 21°C. Ambient
noise in the lab was ~17 dBA. Maximum load temperatures were recorded ~20 minutes
into a CPU stress test with CPUBurn after the core temperature had stabilized.
Because it is difficult to swap the stock fan, we did not
follow our standard
testing methodology, which calls for the use of a SPCR reference fan
so that cooling efficiency of the heatsink can be tested relative to a constant
reference airflow. Instead, the stock fan was left on the unit, and both noise
and cooling performance were tested at 12V, 9V, 7V, and 5V.
RESULTS
| Arctic Cooling Freezer 4 with Stock
Fan |
|
Thermal Conditions
|
Load Temperature
|
Rise from Ambient
|
°C/W MP
|
°C/W TDP
|
SPL
|
|
CPUBurn @ 12V
|
42°C
|
21°C
|
0.27
|
0.30
|
|
|
CPUBurn @ 9V
|
43°C
|
22°C
|
0.28
|
0.32
|
|
|
CPUBurn @ 7V
|
46°C
|
25°C
|
0.32
|
0.37
|
|
|
CPUBurn @ 5V
|
52°C
|
31°C
|
0.39
|
0.45
|
|
°C Rise from Ambient: Temperature rise above ambient at
load
°C/W MP / TDP: Temperature rise per Watt, based on Maximum
Power (79W) or Thermal Design Power (69W) rating of CPU
SPL: Sound Pressure Level in dBA/1m measured with high accuracy
B & K SLM at 1 meter
|
At stock voltage, the fan included with the Freezer 4
is not quiet. The fan produces a fairly even hum that's quite noticeable. Luckily,
the hum is very directional and is most audible in a 25°~30° cone extending from
the hub of the fan. A well damped case should have
a significant impact on the noise at 12V. The fan also produces a constant low level buzz
that does not change in volume through most of the voltage range. It is most
audible in the 7-9V range, but it drops enough in volume at 5V to be considered
inaudible inside a computer case.
Both the fan and the heatsink itself tolerate undervolting quite well. 7V probably provides the best compromise between cooling and
noise. At this level the pitch of the motor noise has dropped almost out of
hearing range. The residual motor noise that it produces at this level would
disappear inside any case of decent quality. The heatsink does not struggle
much under this reduced airflow; the burn temperature at 7V rose only 4°C
compared to the 12V result. At 46°C, there's a bit of headroom for hotter
CPUs as well.
For the noise obsessed, a medium-powered system could probably be run
safely (but with high temperatures) with the fan at 5V. At this level the Freezer
is, for all practical purposes, silent. Our measurement of 17 dBA at this level
is more of a guess than a measurement, as the ambient noise was too high to
measure it reliably at one meter.
The thermal performance is just shy of SPCR favorites, the Zalman
7000 series and the Thermalright
XP series. The comparison to the Zalman 7000 is especially apt, as this
heatsink also features a fan that is not easily changeable. Although the Zalman
is capable of better cooling at comparable voltages, the Freezer is quieter
at these voltage levels.
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