Clock Rates, Temperature & Noise
Temperature & Clock Rates
Our first test charts the GPU's thermal performance through an OpenGL-based brick-building loop, while also monitoring clock rate. Incidentally, frequency hardly decreases over time, even when the GPU's diode crests the 90° mark. AMD set the old BIOS' temperature limit to 95°C. We think that's a bit too high for a professional graphics card.
Fortunately, the card operates closer to the GPU's sweet spot than AMD's higher-clocked Radeon RX 480, which uses a lot more power and can't maintain its initial clock rate. The Radeon Pro WX 7100 is generally more conservative, enabling its single-slot cooling solution.
The temperatures are significantly higher than 90°C due to an inadequate fan curve. This isn't good for long-term durability.
Now the temperature is 85°C, eight degrees lower than what we measured with the old BIOS. That's a significant improvement.
Infrared Measurements: Old vs. New BIOS
But is the ideal of single-slot cooling really as admirable as it's believed to be?
The two test scenarios push a demanding load. The OpenGL-based wall-building benchmark matches our Metro Last Light gaming workload almost to the watt. Both tasks seem almost overwhelming to the old BIOS; the VRMs especially generate considerable heat.
There are two reasons for this. First, the top of the small VRM cooler receives too-little airflow as a result of diminished pressure. Second, the HEXFETs with metal housings create a lot of waste heat that ends up in the PCB and not the heat sink.
The new BIOS counters that first problem with more air pressure, enabled by a higher fan speed.
This region is particularly impacted by the stress test, even though average power consumption does not rise. The voltage changes are moderate, after all, and the MOSFETs' efficiency curve clearly shifts in the wrong direction. Here's a look at the old BIOS:
Unfortunately, the issue related to the HEXFETs also relates to AMD's approach to component layout. Superimposing the front and back of the board shows that the gate drivers are located directly under the high-side MOSFET. Its waste heat causes a hot spot under the gate driver.
The new BIOS and drivers together offer a vastly improved infrared image.
Fan Speeds and Noise Output
Of course, higher fan speeds usually affect acoustics negatively. It appears AMD wanted to keep noise tightly under control with an original rotational speed of less than 3000 RPM. That led to the elevated temperatures documented in our infrared measurements:
After consulting with AMD's product management, we learned that we should have expected up to 3600 RPM at the temperatures we reached. With the help of a new BIOS, those temperatures are far tamer, protecting the GPU and its surrounding components.
On that note, let's have a look at the resulting sound profile under a taxing OpenGL-based load.
As always, we measure acoustics using a special water-cooled systems in an anechoic chamber. The practical lower limit of this environment is 22 dB(A).
|Test System and Hardware|
|Microphone||NTI Audio M2211 (with Calibration File, Low Cut at 50Hz)|
|Amplifier||Steinberg UR12 (with Phantom Power for Microphones)|
|System||Graphics Card Test System with Optimized Water Cooling - Intel Core i7-5930K @ 4.2GHz, Water-Cooled - Crucial Ballistix Sport, 4x 4GB DDR4-2400 - MSI X99S XPower AC - 1x Crucial MX200, 500GB SSD (System) - 1x Corsair Force LS, 960GB SSD (Applications, Data) - be quiet! Dark Power Pro, 850W Power Supply Unit (PSU)|
|Water Cooling||- Alphacool VPP655 Pump (Undervolted) - Alphacool NexXxos CPU Cooler - Phobya Balancer - Alphacool 24cm Radiator - 2x 12cm Noiseblocker eLoop Fan @ 400 RPM|
|Measurement Chamber||Custom-Made Proprietary Measurement Chamber, 3.5 x 1.8 x 2.2m (LxDxH)|
|Measurement Position||Perpendicular to Center of Noise Source(s), Measurement Distance of 50cm|
|Measurement Data||- Noise Level in dB(A) (Slow), Real-time Frequency Analyzer (RTA) - Graphical Frequency Spectrum of Noise|
Nearly 41 dB(A) for the old BIOS is acceptable for such a thin card. There's no easy way to dissipate 140W or outsmart physics. But the associated thermal issues we've already covered necessitated changes that'd inherently affect noise.
With the new BIOS, the fan spins anywhere from 450 to 500 RPM faster. The extra 3.5 dB(A) we measure isn't a deal-breaker, but in our subjective opinion, the noise sounds almost twice as loud.
Frankly, though, when we look at the trade-offs, a louder, more durable card is preferable to one that overheats quietly. There is no magic at play; you simply need to push enough air through a single-slot cooler to make it viable.