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Cooling System: Performance and Noise Level

As opposed to PowerColor’s triple-slot cooler or ASUS’s liquid cooling system, the reference cooler is designed in two-slot form-factor. The card is 36 mm thick, which is smaller compared to the GTX Titan or the GTX 690. The plastic casing with three fans is secured on the PCB with a few small screws. After taking it off, we could see two separate aluminum heatsinks on the GPUs and one narrow copper heatsink on the power components:

The GPU heatsinks are secured with four screws each. The frame on the memory chips and other components is harder to take off, but not as hard as on the Titan, for example. So, we managed to dismantle the whole cooler:

 

Although the GPU heatsinks are only 11mm thick, each contains four copper heat pipes, 6 mm in diameter:

The pipes go out of the copper base and pierce the thin aluminum fins. The components of the cooler are all soldered to each other.

The whole arrangement is cooled with three 90mm fans (the impeller is 86 mm in diameter), which reminds us of the superb graphics card coolers from Arctic.

The speed of the fans is PWM-regulated in a range of 1000 to 4500 RPM. Judging by their labels, these FDC10U12D9-C fans are manufactured by AMD’s long-time partner NTK Limited.

The fans run on dual ball bearings which are going to serve for a long time but are unlikely to be quiet. According to the label, the peak power consumption of one fan is 5.4 watts. The startup voltage is less than 3 volts.

To check out the cards temperatures we used five runs of the Aliens vs. Predator (2010) benchmark at the highest visual quality settings, at a resolution of 2560x1440 pixels, and with 16x anisotropic filtering and MSAA 4x. We used MSI Afterburner 3.0.0 beta 10 and GPU-Z version 0.7.1 for monitoring of temperatures inside the closed system case, which configuration is discussed in detail in the corresponding chapter of the roundup. All tests were performed at 25°C room temperature.

Let’s see how efficient the cooler is when its three fans are regulated automatically:


Auto fan mode

The Radeon HD 7990 is very hot and very noisy. When the cooler’s fans are regulated automatically, one GPU is 90°C hot and another is 79°C hot. The fans accelerate up to 3890 RPM at that. You can imagine how noisy the card is in that case!

When the maximum speed was selected for the fans, the temperature of the hotter GPU was only 1°C lower whereas the other GPU got 11°C colder.


Maximum fan speed

We suspected that the large difference in temperature was due to imbalanced load between the GPUs, which can be seen in the diagrams. There was another factor, though. As soon as we took off the side panel of our computer case, the GPUs got substantially colder:


Maximum fan speed (open system case)

Although the difference between the two GPUs was still up to 16°C, the temperatures were more acceptable than in the closed computer case.

The noise level of each cooler was measured between 1:00 and 3:00 AM in a closed room about 20 m2 big using CENTER-321 electronic noise meter. The noise level for each cooler was tested outside the system case when the only noise sources in the lab were the cooler and its fan. The noise meter was installed on a tripod and was always at a 150 mm distance from the cooler fan rotor. The tested cooling systems were placed at the edge of the desk on a sheet of polyurethane foam. The lowest noise reading our noise meter device can register is 29.8 dBA and the subjectively comfortable noise level in these testing conditions was around 36 dBA (do not mix it up with low noise level). The fan(s) rotation speed was adjusted in the entire supported range using our precise in-house controller by changing the voltage with 0.5 V increment.

Now let’s compare the AMD Radeon HD 7990, GeForce GTX Titan and GeForce GTX 690 in terms of noise level (the top speeds of the fans are marked with dotted lines of the corresponding colors):

The dual-processor newcomer is unfortunately the noisiest of the three. The difference is quite substantial in the automatic fan regulation mode. To put it short, the Radeon HD 7990 is a noisy graphics card. The GeForce GTX 690 isn’t quiet in 3D applications, either, but its noise is more agreeable to the ear. The GeForce GTX Titan works quieter than both dual-processor products, which is its indisputable advantage over them.

 
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