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Our test procedure is an in-system test, designed to determine whether the
cooler is adequate for use in a low-noise system. By adequately cooled,
we mean cooled well enough that no misbehavior related to thermal overload is
exhibited. Thermal misbehavior in a graphics card can show up in a variety of
- Sudden system shutdown or reboot without warning.
- Jaggies and other visual artifacts on the screen.
- Motion slowing and/or screen freezing.
Any of these misbehaviors are annoying at best and dangerous at worst
dangerous to the health and lifespan of the graphics card, and sometimes to
the system OS.
Measurement and Analysis Tools
- ATI Tool
version 0.26 as a tool for stressing the GPU
P6 processor stress software.
version 4.33 to show CPU & GPU temperature
Power Angel AC power meter, used to monitor the power consumption
of the system
- A custom-built internal variable fan speed controller to power the
- Calibrated strobe light to measure fan RPM
- A custom-built external variable fan speed controller to power the
VGA heatsink fan (if applicable)
- Bruel & Kjaer (B&K) model 2203 Sound Level Meter, used to
accurately measure SPL (sound pressure level) down to 20 dBA and below.
A summary of how our video card/cooler test platform is put together can
be found here.
Our main test consists of ATITool's artifact scanner running in conjunction
with CPUBurn to stress both the graphics card and processor simultaneously.
It is a realistic test that mimics the stress on the CPU and GPU produced by
a modern video game, only more consistantly. The software is left running until
the GPU temperature stabilizes for at least 10 minutes at which point, both
the CPU and GPU temperatures are recorded. In addition we also take measurements
of the system's overall noise level and power consumption using a B&K Sound
Meter and a Seasonic Power Angel respectively. If the heatsink has a fan, the
procedure is repeated at various fan speeds while the system fan is left at
the lowest setting of 7V. If it is a passive cooler, the system fan instead
is varied to study the effect of system airflow on the heatsink's performance.
If artifacts are detected in ATITool or other instability is noted, the heatsink
is deemed inadequate to cool the video card in our test system.
Preliminary testing is also done at idle, and with only CPUBurn running for
comparison. For idle results, the system is left stagnant for 10 minutes before
ATITool is loaded and the first temperature it reports is used. We do this because
on our test platform, after ATITool is loaded, it puts some kind of stress on
the GPU, causing the temperature to climb immediately (even if it is left idle
for hours beforehand) and the power consumption to increase by approximately
10W. We theorize that initially the card is in 2D mode, either underclocked
or undervolted (or possibly both) and that ATITool automatically puts it in
3D mode, which would account for the rise in temperature and power draw. ATITool
is left running in the background for the remainder of testing which is why
the GPU temperature during CPUBurn will appear higher compared to idle. Consider
this the difference between 2D idle and 3D idle.
The ambient conditions were 25°C and 14 dBA at the time of testing.
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