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Cooling System and Noise Level

The cooling system of the Sapphire Radeon HD 7950 OC is almost a perfect copy of the cooler of the Sapphire Radeon HD 6970 DualFan but is now called Dual-X:

Its aluminum heatsink is based on five heat pipes, three of which are 6 millimeters in diameter. The two outermost pipes are 8 millimeters in diameter.

The heat pipes are soldered to the copper base which has a special protrusion for the GPU die:

This is in fact the only difference of the Dual-X cooler from its DualFan predecessor except for the metallic frame for the memory chips and power components:

The two 90mm fans are secured within the cooler’s plastic casing:

Like the Sapphire Radeon HD 6970’s cooler, this one employs FirstDFD7010H fans.

The speed is PWM-regulated within a range of 1100 to 3200 RPM. The peak power consumption of each fan is 4.2 watts.

We checked out the card’s temperature while running Aliens vs. Predator (2010) in five cycles at the highest settings (2560x1600, with 16x anisotropic filtering and 4x full-screen antialiasing). We used MSI Afterburner 2.2.0 Beta 12 and GPU-Z 0.5.8 as monitoring tools. This test was carried out with a closed system case at an ambient temperature of 26°C. We didn’t change the card’s default thermal interface.

Let’s see how efficient Sapphire’s cooler is with its fans being regulated automatically and at their maximum speed:


Automatic fan speed mode

Max fan rotation speed

When regulated automatically, the fans have a peak speed of 1800 RPM and the GPU temperature is only 63°C. At the maximum speed of the fans the GPU is no hotter than 54°C. This is an excellent result, especially as the GPU is pre-overclocked by 100 MHz. We knew the cooler to be effective after our tests of the Sapphire Radeon HD 6970 DualFan and it proves its efficiency once again on the new card. By the way, when we switched to the second BIOS (the more extreme version according to Sapphire), the cooler's fans would work at the same speeds. The card didn't seem to think it necessary to speed the fans up under our test conditions. Now, what about the noise factor?

We measured the level of noise using an electronic noise-level meter CENTER-321 in a closed room about 20 sq. meters large. The noise-level meter was set on a tripod at a distance of 15 centimeters from the graphics card which was installed on an open testbed. The mainboard with the graphics card was placed at an edge of a desk on a foam-rubber tray. The lower limit of our noise-level meter is 29.8 dBA whereas the subjectively comfortable (not low, but comfortable) level of noise when measured from that distance is about 36 dBA. The speed of the graphics card’s fans was being adjusted by means of a controller that changed the supply voltage in steps of 0.5 V.

We’ve included the results of the reference AMD Radeon HD 7970 and the Sapphire Radeon HD 6970 Dual Fan cooler into the next diagram. Here are the results:

As we can see, the noise curve for Sapphire Radeon HD 7950 OC repeats traces the curve of the Sapphire Radeon HD 6970 Dual Fan, which is quite logical, because the coolers differ only by the decorative inserts and “shields”. Nevertheless, the new Sapphire graphics card works much quieter, because the maximum speed of its cooling fans in automatic mode is 1800 RPM, while Sapphire Radeon HD 6970 Dual Fan has a higher maximum of 2580 RPM. In 2D mode the graphics card cooler is completely undetectable against the background of the quiet system case. The cooler of XFX R7970 Double Dissipation Edition produces more noise.

 
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