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This sturdy modified LX-6A19 (D8000) case from Cool Cases housed our test
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.
The test system was built around the coolest Intel Prescott-based processor
we had on hand. It's a reasonable example of a mid-powered system that is fairly
easy to keep quiet. Almost all AMD-based processors should run cooler than our
Pentium 520, and almost all Intel-based desktop processors run hotter.
520 processor (P4-2.8 Prescott, 1Mb cache, 800 MHz FSB in 775 casing).
The combined power draw for the processor and the VRMs on the test motherboard
was measured at 85.3 watts. Intel's official TDP is 84 watts.
i945Ga-PHS motherboard - Intel i945Ga Chipset; built-in VGA.
- CoolerMaster Hyper 48
heatsink, cooled by a Nexus 92mm fan undervolted to 7V.
DDR2 RAM, 1024 MB
- Seagate Momentus 5400.2
120 GB, 2-platter drive, suspended in a NoVibes
III just inside the front intake vent.
- Antec Neo HE 430
ATX12V 2.01 compliant power supply, with a custom-built fresh air duct to
ensure that the internal fan did not ramp up during testing.
- Modified case from Cool
Cases, outlined in detail below.
- Nexus 120mm
fan controlled by a variable voltage fan controller.
Measurement and Analysis Tools
System airflow is quite good, allowing the CPU and system fans to run at close
to inaudible speeds without compromising system cooling. The intake is about
the size of a 120mm fan. The only restriction is an air filter. A much more
restrictive cover for the filter was removed because it impeded the airflow
The one and only intake...
...and the same view, with the bezel removed.
There is only one point of exhaust: The 120mm case fan, which can be run at
a number of different speeds. The 80mm fan in the Neo HE power supply was taken
out of the picture by using a custom-built duct to ensure that the fan never
ramped up. The amount of airflow through the system can be controlled by adjusting
the speed of the case fan, thereby giving us a way of controlling how difficult
the thermal environment inside the case is.
A fresh air duct isolates the power supply from the rest of the system.
Only one possible point of exhaust: The orange case fan.
The fan in the power supply draws its air from a duct that does not interact
with the rest of the system airflow.
The airflow in our test rig is typical of an ATX case. Air flows in through
the intake near the bottom of the front panel, and is pulled up to the top rear
corner. Most of this air will bypass the expansion cards altogether, but a small
amount will be pulled across the rear of the card as it is pulled towards the
CPU heatsink and the case fan. All of the air will exit the case via the exhaust
The air will flow from the lower right to the upper left, drawing a small
amount of air across the VGA card.
The coolers were installed on an AOpen
Aeolus PCX6800GT-DVD256 a medium-powered video card that features
a thermal sensor build into the GPU core. The accuracy of the sensor is unknown,
but it is good enough to make relative judgments between the various coolers.
This GeForce 6800GT has stood up to a year's worth of abuse around the SPCR
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