Cooling & Noise
There’s a direct relationship between power consumption and waste heat, and it's the thermal solution's job to cope with the latter. ASRock deliberately omits a backplate from its design, which is fine because it wouldn't have served any purpose except to look good. Thus, all of the cooling is achieved by the heat sink and fans up front.
A copper sink draws thermal energy from the GPU, while two 6mm heat pipes and a single 8mm one dissipate it through a large fin array. The base surrounding that copper block is made of aluminum, and it helps cool the memory modules through thermal pads.
Most baffling to us are the GPU and VRM sinks connected by a 6mm heat pipe. This pipe is heated from both ends, with nothing in between to cool it off. As a result, it can't be particularly efficient.
The horizontally-oriented cooling fins have quite a bit of space between them. As such, a deeper/wider sink would have been better, complemented by fans blowing air in a more turbulent manner. The way this implementation is built, fans optimized for static pressure don't cool as well.
|Cooling System Overview|
|Type Of Cooler||Air cooling|
|GPU Cooling||Nickel-plated copper heat sink|
|Cooling Fins||Aluminum, horizontal alignmentWide, not inclined|
|Heat Pipes||2x 6mm, 1x 8mm nickel-plated copper composite|
|VRM Cooling||Six GPU phases via dedicated VRM sink|
|RAM Cooling||Memory cooling via heat sink base|
|Fans||2x 8.5cm fans (8.7cm opening), nine bladesSemi-passive control|
Fan Curves & Noise
ASRock implements a semi-passive mode that remains active at idle with the card drawing ~12W. As the Phantom Gaming X warms up, its fan curve proves to be fairly conservative. After a quick ramp-up under load, the speed increase tapers off somewhat, averaging around 2500 RPM in a closed case. The Phantom Gaming X is clearly sensitive to its ambient environment, though: on an open test bench, the fans spin almost 500 RPM slower and keep the card about five degrees cooler.
The picture doesn't look much different in FurMark. In short, ASRock's thermal solution gets the job done. But its two fans also have to spin quite a bit faster in a closed case to abide ASRock's temperature target.
Again, the Phantom Gaming X's cooling solution leaves no headroom for slower-spinning fans.
|Fan RPM & Noise Measurements|
|Fan RPM, Open Test Bench, Maximum||2238 RPM (Peak)|
|Fan RPM, Open Test Bench, Average||2198 RPM (Warmed up)|
|Fan RPM, Closed Case, Maximum||2522 RPM (Peak)|
|Fan RPM, Closed Case, Average||2496 RPM (Warmed up)|
|Noise (Air) Range||41.6 dB(A) (Warmed up, open test bench)45.3 dB(A) (Warmed up, closed case)|
|Noise (Air) Idle||0 dB(A)|
|Noise Characteristics / Subjective Impressions||Slight bearing noiseSome motor noises below 1 HzModerate air and turbulence noisesHardly any voltage converter noise|
After adjusting the fans up to the speeds measured in a closed case, our acoustic equipment reports a noise output of 45.3 dB(A). That's well above the psychologically (and acoustically) important 40 dB(A) limit at 50cm. The following frequency spectrum analysis gives us a better idea where the sound comes from.
Make sure your case has good airflow. It's much easier to add a couple of quiet case fans that keep air moving than messing with the parameters of ASRock's thermal solution. In the end, though, don't expect the Phantom Gaming X to be a quiet card.
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