Cooling & Noise
Cooling Solution & Backplate
There’s a direct relationship between power consumption and waste heat, and it's the thermal solution's job to cope with the latter. This is exactly where we run into minor issues.
In order to stabilize the PCB and cool those two isolated voltage converters, Asus utilizes a special frame that's screwed to the slot cover and matches up with the backplate. In this case, it's only responsible for cooling one phase, which we've already seen running at significantly lower temperatures than the surrounding components.
Asus coats the inside of the backplate in black, so thermal energy from components on the PCB is absorbed more easily. But unlike most of its competitors, the company neglects to use a thermally-conductive pad between the board and backplate.
Fortunately, MSI, Gigabyte, EVGA, Galax, and others use this inexpensive approach to improve heat dissipation on their cards. Hopefully Asus follows suit sooner than later.
In comparison, the implementation of a back-lit logo is functionally useless, even if it looks cool.
|Cooling System Overview|
|Type of Cooler||Air cooling|
|GPU Cooling||Nickel-plated copper heat sink|
|Cooling Fins||Aluminum, vertical alignmentNarrow configuration, not inclined|
|Heat Pipes||6x 6mm Nickel-plated copper composite material|
|VRM Cooling||Seven phases via an extra VRM sink in the coolerOne phase via cooling frame|
|RAM Cooling||Cooling of HBM2 modules via heat pipe|
|Fans||3x 9cm fans (9.2cm opening), 11 blades, Semi-passive fan control|
|Backplate||Blackened aluminumNo cooling function|
In addition to the sink for some of the voltage converters, six 6mm heat pipes made of nickel-plated composite material are responsible for transporting thermal energy from the GPU to different parts of the finned cooler.
The GPU heat sink looks like a polished plate, creating an extra-smooth surface.
Fan Curves & Noise
Semi-passive operation is implemented through an on-board controller that reports an exact tachometer signal, even if AMD's WattMan still uses PWM values for the fan curve stored in the BIOS. This curve ensures that the GPU doesn't overshoot its 75°C target temperature.
After a period of heavy cooling during warm-up, the fans slow down and stabilize. However, Asus tried a little too hard to optimize for noise, resulting in fan speeds that accelerate and decelerate under load. The company probably should have dialed in a slightly higher fan speed to avoid this behavior.
We can also see how sensitive this card is to operating in a closed PC case. Compared to the custom solutions from Sapphire and Gigabyte, the fan speeds required to maintain AMD's target temperature are significantly higher than those of the competition. Heat soaking into the GPU package from the voltage regulation circuitry is partially to blame.
Little changes during our stress test. While the cooler and its three fans do work well enough, they'd need to spin faster in order to keep us from worrying about thermal bottlenecks.
The board's cooling implementation has no available headroom to let the fans spin more slowly. Asus seems to have optimized for air volume. But in a closed case, the ROG Strix Radeon RX Vega 64 8GB OC Edition is still louder than its competition.
|Fan RPM & Noise Measurements|
|Fan RPM, Open Test Bench, Maximum||1847 RPM (Peak)|
|Fan RPM, Open Test Bench, Average||1280 RPM (Warmed up)|
|Fan RPM, Closed Case, Maximum||2119 RPM (Peak)|
|Fan RPM, Closed Case, Average||1666 RPM (Warmed up)|
|Noise (Air) Range||33.2 (Minimum) to 44.5 dB(A)|
|Noise (Air) Average||34.8 dB(A) (Warmed up, Open bench table)38.3 dB(A) (Warmed up, Closed case simulation)|
|Noise (Air) Idle||0 dB(A)|
|Noise Characteristics / Subjective Impressions||Low-frequency bearing noisesSome motor noises below 1 HzModerate air and turbulence noisesSlight voltage converter noises|
This snapshot illustrates the entire frequency range of our laboratory measurements, adding some data to our subjective observations. The alternating fan speeds we mentioned previously are clearly visible.
Once fan speeds settle down, the frequency spectrum evens out. The 34.8 dB(A) noise output we measure from an open test bench is the result so many other sites found so praiseworthy about Asus' card. However, if you set the fans to spin as fast as they do in a closed case, 38 dB(A) is exceeded.
Make sure your chassis has plenty of airflow if you plan to install Asus' ROG Strix Radeon RX Vega 64 8GB OC Edition. After all, it's easier to deal with heat using good case fans than forcing the graphics card's thermal solution to struggle against a warm ambient environment. You'll hear the difference.
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