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Cooling System: Efficiency and Noisiness

Here’s how the cooling system deployed on the GeForce GTX 690 is supposed to work:

The GPUs have nickel-plated aluminum heatsinks with copper base designed as a vapor chamber. The power system components and memory chips are cooled by a metallic plate that carries a 9-blade 83mm impeller with PWM-based regulation.

The air from that fan goes through the slim heatsink fins and gets exhausted through the vent grid in the mounting bracket as well as through the opening in the other side of the casing. Some of the hot air remains inside the system case, which seems to be the only downside of this cooler design. On the other hand, thanks to the fan working both ways, the GPUs are going to have about the same temperature, which may be beneficial for overclocking.

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 antialiasing). We used MSI Afterburner 2.2.0 and GPU-Z 0.6.0 as monitoring tools. This test was carried out with a closed system case at an ambient temperature of 23°C. We didn’t change the card’s default thermal interface.

Let’s see what temperature the card has when its fan is regulated automatically:

We’ve got interesting results here. The GPUs were 79 and 82°C hot during the test while the top speed of the fan was 2160 RPM. But the most interesting thing is that the GPU clock rate was boosted from 915 MHz not to the specified 1019 MHz but to 1071 MHz. GPU-Z and MSI Afterburner both report the same number, so it’s not an inaccuracy of our monitoring tools.

At the maximum fan speed of 2970 RPM the GPUs had peak temperatures of 71 and 73°C.

The numbers are quite normal for a dual-GPU card and the two GPUs do have similar temperature.

We should note that the speed of 2160 RPM in automatic mode and the maximum speed of 2970 RPM set manually are rather low even for single-GPU products, let alone dual-GPU ones. Nvidia puts an emphasis on the fact that the GeForce GTX 690 is actually 4 dBA quieter than the reference GeForce GTX 680.

Let’s check this out, though, using our own method.

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 reference GeForce GTX 680 and Radeon HD 7970 cards into the next diagram. Here are the results (the vertical dotted lines indicate the top speed of the fans in automatic regulation mode):

Well, the GeForce GTX 690 doesn’t meet our expectations as its noise graph goes higher than the GeForce GTX 680’s and merges with the Radeon HD 7970’s graph after 1650 RPM. However, thanks to the lower speed of the fan, the GTX 690 is quieter than the HD 7970 and comparable to (yet not quieter than) the GTX 680. The GeForce GTX 690’s fan worked smoothly, without vibrations or rattling or anything. The card was silent in 2D mode.

 
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