AMD RX Vega 64 & Vega 56 Performance Review



  • Author: SKYMTL
  • Date: August 14, 2017
  • Product Name: RX Vega 64 / RX Vega 56
  • Warranty: 3 years

Understanding Power Profiles & The HBCC

In an effort to give users finer grain control over Vega’s voracious appetite for power, AMD has implemented a slider within their Wattman overclocking utility. Basically it allows you to modify the card’s behavior with a few clicks rather than going through the trial and error of overclocking or underclocking. The default position is Balanced which evens out clock speeds while keeping Vega’s fan curve to relatively decent speeds. On the flip sides of this, Power Save is meant to deliver a quieter gaming experience by clocking the core to lower speeds and delivering an optimal performance per watt quotient. Meanwhile Turbo is basically a balls-to-the-wall setting the sacrifices power consumption and acoustics for higher overall performance.

According to AMD, Power Saver can increase a Vega 64’s performance per watt ratio by up to 25% while the delta between Turbo and Balanced is somewhere in the neighborhood of 3% in terms of actual framerates. What this tells us is that Vega has been pushed to its absolute limit in an effort to compete with NVIDIA’s Pascal architecture. For the purposes of testing within this review, we’ve left the slider in its default Balanced position.

All Vega cards also have a small VBIOS switch located on their outside edge which toggles between two different power “modes”. They ship in the “primary” (or higher wattage) position whereas the secondary position allows for even lower input requirements. When used in conjunction with Power Profile slider in Wattman, you can reduce power by up to 50W.

A Quick Mention about HBCC

AMD’s High Bandwidth Cache Controller was initially designed for the professional market to grant the GPU core direct access to high speed storage subsystems. It would then use those storage systems (be it an SSD array or onboard memory) as a partial caching partition for page files.

The HBCC implementation in Vega 10’s desktop version is a bit different. It allows you to dynamically utilize system memory as part of the GPU’s cache or memory partition. The 8GB of HBM video memory should be more than enough for any of today’s games but there’s no guarantee 8GB will be enough for future applications. To compensate for this, AMD has added a slider with Radeon Settings that sets aside system memory for use if the software detects local video memory is running low. It will then move unused bits to the slower system memory for use later, freeing up space on the HBM for higher priority packets. This is actually done seamlessly as the game engine will detect the total capacity of the HBM plus the system memory.

For the time being at least, this setting won’t have any use unless you somehow find a game that gobbles up more than 8GB of video memory. However it could be a game changer for HBM GPUs which typically have a smaller memory footprint than their GDDR-equipped alternatives.

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