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Cooling System: Efficiency and Noise Level

The DirectCU II cooler claims to be 20% more efficient and 3 times quieter than AMD’s reference solution. It really seems to be capable of that, featuring a large aluminum heatsink with heat pipes and two fans covered with a metal casing.

There are as many as five nickel-plated copper pipes here, two of which are 6 mm in diameter. Two more pipes are 8 mm and there’s also a 10mm pipe there.

The heatsink features direct-touch technology meaning that the heat pipes have direct contact with the GPU.

The thermal grease imprint indicates that the GPU only contacts with the two 8mm pipes and with one half of the 10mm pipe. The outermost 6mm pipes transfer heat from the sides of the adjacent pipes only, which is hardly an efficient solution. The pipes and heatsink fins are soldered to each other. The power components in the back part of the PCB are equipped with a small aluminum heatsink with a thermal pad. The solid-state capacitors (located near the video outputs) and the memory chips have no heatsinks and are cooled by the air flow from the fans.

The fans have identical motors but different impellers. They are both about 95 mm in diameter.

The fan above the GPU has a dual impeller with two sets of differently shaped blades. ASUS calls it CoolTech and showcases its benefits in the following demo:

The original fan is indeed more efficient than the ordinary one. The question is why didn't ASUS install two such fans on the card? The fans are PWM-regulated in a range of 1000 to 3000 RPM.

To measure the temperature of the ASUS Radeon R9 290 DirectCU II graphics card we ran Aliens vs. Predator (2010) five times at the maximum visual quality settings, at a resolution of 2560x1440 pixels, with 16x anisotropic filtering and with 4x MSAA.

We used MSI Afterburner 3.0.0 beta 18 and GPU-Z version 0.7.7 to monitor temperatures inside the closed computer case. The computer’s configuration is detailed in the following section of our review. All tests were performed at 25°C room temperature.

With the fans regulated automatically, the GPU is 80°C hot while the fans rotate at 1800 RPM (47%).


Auto fan speed mode

This is 14-15°C better than the result of the reference AMD Radeon R9 290 tested under the same conditions. Most importantly, the ASUS version doesn’t drop its GPU frequency in this test, so the DirectCU II copes with its job very well.

If the fans are manually set at their maximum 3000 RPM, the top GPU temperature is only 69°C.


Max fan speed mode

The graphics card becomes rather noisy at that, though.

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 fans was being adjusted by means of a controller that changed the supply voltage in steps of 0.5 V.

We’ll compare the noise level of the ASUS Radeon R9 290 DirectCU II with that of the reference R9 290 from AMD. We also include the results of the Nvidia GeForce GTX 780 Ti and the original MSI GeForce GTX 780 Ti Gaming for the sake of comparison. The vertical dotted lines mark the top speed of the fans in the automatic regulation mode. Here are the results:

As you can see, the ASUS Radeon R9 290 DirectCU II is quieter than the reference card but only because its fans have lower speed when regulated automatically. Thanks to the efficient cooler design, the fans rotate at 1800 RPM, making the ASUS version much quieter than the reference R9 290. We wouldn’t call the ASUS comfortable in 3D applications, though. It is persistently audible against the background noise of a quiet computer. It is only in 2D applications when the GPU and graphics memory are clocked at 300 and 600 MHz that the card calms down. The fans with EBR bearings don’t produce any unwanted sound at any speed, at least when the graphics card is new. We can’t vouch for their behavior in a year, for example.

 
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