Arctic Cooling Accelero S1 VGA Cooler

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Full details of our latest VGA test system is detailed in a recent article. Our test procedure is an in-system test 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 ways, including:

  • 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.

Test Platform

    The exterior view of our test platform.

The Antec P180 case has two front 120mm intakes — the bottom one feeds fresh air to the hard drive and power supply section while the top one allows airflow into the rest of the system. The stock filter and door over the intake vent for the main chamber are removed — replaced with the metal mesh for the top panel 120mm fan. The filter for the lower PSU/HDD chamber is retained, but its cover door is also removed to reduce airflow impedance. The front door is cast away as well to improve airflow. The top three optical drive bays are covered with a block of open-cell foam which allows some air to flow in but also absorbs much of the internal sound from coming out.

The internals of our new testbed.

The processor is cooled by a modified Gigabyte G-Power 2 Pro without its plastic shroud utilizing a Scythe Slip Stream 120mm 500RPM fan, connected directly to the motherboard's CPU fan header — it is completely inaudible. Above it, a block of foam is positioned on the ceiling over top fan vent, which also draws some air in when the system is running.

The only system fan is a Nexus 120mm mounted in the rear exhaust position with silicon rubber nubs made expressly to reduce vibration conduction into the case. It is powered by the PSU through to a customized fan speed controller using zener diodes. A knob protruding from the wall of foam at the front allows the fan voltage to be easily varied.

The power supply is a Seasonic S12-600 with the stock fan replaced by a Scythe Slip Stream 120mm 800RPM fan, hard-wired to run at 5V. The fan just barely starts up, and spins extremely slowly, at ~400RPM. Air expelled from the PSU is only mildly warm, even during long sessions of high power testing.

The notebook hard drive is suspended in the lower drive bay with zip ties and cloth elastic with a 2mm round cross-section. No vibration from the drive can be felt on the drive bay. Foam is attached to both sides of the compartment divider as an extra silencing measure.

The overall noise level of the system is excellent at only ~19 dBA@1m with the system fan @ 7V. For comparison, during the quietest moments in our lab with all the computers turned off, the ambient noise level is around 17 dBA.

Measurement and Analysis Tools

  • ATI Tool version 0.26 as a tool for stressing the GPU and to show GPU temperature
  • CPUBurn P6 processor stress software.
  • SpeedFan version 4.33 to show CPU temperature
  • Seasonic 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 system fan
  • 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.

Heatsinks are installed on an ATI Radeon X1950XTX (if compatible) — a high-powered video card that features a thermal sensor built into the GPU core. The accuracy of the sensor is unknown. The video memory heatsink is usually left on unless it interferes with the VGA cooler.

Our test card: a Radeon X1950XTX.

Our main test consists of ATI Tool'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 consistently. 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 ATI Tool or other instability is noted, the heatsink is deemed inadequate to cool the video card in our test system. Usually artifacts begin to appear when the GPU temperature reaches between 90°C and 95°C.

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 ATI Tool is loaded and the first temperature it reports is used. We do this because on our test platform, after ATI Tool 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 ATI Tool automatically puts it in 3D mode, which would account for the rise in temperature and power draw. ATI Tool 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.

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