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Cooling System: Efficiency and Noise

Sapphire’s original Dual-X cooler hasn’t changed since we last saw it on another product. It consists of an aluminum heatsink with heat pipes and a plastic casing with two fans.

As opposed to the top-end Sapphire Radeon HD 7970 and HD 7950 Dual-X, the Sapphire Radeon HD 7870 OC has four rather than five heat pipes, which is justifiable by its lower heat dissipation.

The two middle pipes are 6 millimeters in diameter whereas the outermost ones are 8 millimeters. The components of the cooler are all neatly soldered to each other.

The power components and memory chips are cooled by a metallic plate with thermal pads:

The Dual-X uses the same fans as before: FirstD’s FD7010H model with 90mm impeller.

The speed of the fans is PWM-regulated within a range of 1100 to 3300 RPM. The peak power consumption of the fans is 4.2 watts.

We checked out the card’s temperature while running Aliens vs. Predator (2010) in five cycles at the highest settings (1920x1080, with 16x anisotropic filtering and 4x antialiasing). We used MSI Afterburner 2.2.1 and GPU-Z 0.6.2 as monitoring tools. This test was carried out with a closed system case at an ambient temperature of 25°C. We didn’t change the card’s default thermal interface.

Let’s see what temperature the card has when its fans are regulated automatically and at the maximum speed of the fans:


Automatic fan mode

Max fan speed

The GPU is only 70°C hot in the automatic regulation mode, the fans reaching 2230 RPM. At the maximum speed of 3500 RPM the GPU is 62°C hot. That’s what we could expect considering the factory overclocking and the high GPU voltage in 3D mode. We can recall that the reference Radeon HD 7870 (at 1000 MHz and 1.1 V) would get as hot as 76°C under the same conditions, so Sapphire’s Dual-X cooler is efficient indeed. But is it quieter than the reference solution?

We measured the level of noise using an electronic noise-level meter CENTER-321 in a closed and quiet 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 bottom 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 fan 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 a reference AMD Radeon HD 7870 into the next diagram for the comparison’s sake (the vertical dotted lines indicate the top speed of the fans in automatic regulation mode):

Oddly enough, the Sapphire Radeon HD 7870 OC is no better than the reference version in noisiness. Yes, the latter is louder at the maximum speed of its fan but keeps somewhat quieter than the Dual-X in the automatic regulation mode. The two 90mm fans of the Sapphire card produce more noise than the single 70mm fan of the reference Radeon HD 7870 when regulated automatically, but we should remember that it’s got higher GPU clock rate and voltage. If overclocked in the same way, the reference card would be much louder. Anyway, we have to admit that neither of these coolers remains comfortable in 3D mode.

 
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