Asus EN8600GT OC GEAR graphics card

Graphics Cards
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TEST METHODOLOGY


Our old modified LX-6A19 (D8000) case from Cool Cases became our test system housing.

Our first test procedure is an in-system test designed to determine the card's power consumption, and whether the card is capable of being adequately cooled in a low-noise system. By adequately cooled, we mean cooled well enough so 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

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 too much.


The one and only intake...



...and the same view, with the bezel removed.

There is only one point of exhaust: The Nexus 120mm case fan running at 7V. Normally we test it at various voltages using a custom fan controller, but for a budget video card with active cooling, it's unlikely increasing the speed of the exhaust fan would make much of a difference. We were more interested in varying the speed of the video card's fan to analyze its performance and noise output. 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.


A fresh air duct isolates the power supply from the rest of the system.



Only one possible points 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 fan.


The air will flow from the lower right to the upper left, drawing a small amount of air across the VGA card.

Thermal and power testing was conducted with the video card's fan at its lowest and default setting with the system in several different states:

1. Idle.
2. Running two instances of CPUBurn.
3. Running two instances of CPUBurn and ATI Tool's artifact scanner to generate as much heat and power draw as possible from both the CPU and GPU.

SpeedFan was used as our temperature measuring tool (the newest version supports GPU temperature monitoring on some cards), and the test results were recorded after the GPU temperature remained constant for approximately 10 minutes. In the final, most demanding test with the video card's fan running at its lowest setting, ATI Tool was left running for 30 minutes and RTHDRIBL for 30 minutes after that. Throughout this step we watched the screen for visual artifacts that might indicate overheating. If either ATI Tool or RTHDRIBL detected artifacts in this minimum airflow and maximum heat test situation, the card would be retested for artifacts in previous applicable test states to identify additional points of failure.

The card is determined to have passed our testing if it managed to survive the duration of testing without ATI Tool or RTHDRIBL detecting any artifacts.

AC system power consumption was measured from the outlet using a Seasonic Power Angel and actual DC power use was estimated/extrapolated using the efficiency figures deduced from our Antec Neo HE 430 review.

During testing the ambient temperature was 21°C and the noise level was approximately 18 dBA.



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