Issue 2

AMD: All of the above. There’s no escaping it. Power consumption has a bearing on a host of key factors in the everyday operation of a gaming PC, including noise levels, heat, size, cost, and performance. That’s true for big, high-end desktops all the way down to thin-and-light gaming laptops. As a result, power efficiency is one of the key metrics we target when designing Radeon™ GPUs. In fact, we were so pleased with what we were able to achieve with our new Polaris architecture that we completed a Carbon Footprint Study so we could better understand the impact of its efficiency improvements.

An example of a recent AMD software offering that’s targeted at “green gaming”, is Radeon Chill, an intelligent power-saving feature for Radeon graphics that dynamically regulates framerate based on movements in-game. It’s designed to reduce system power consumption while maintaining the end-user gaming experience.

GGN: What technological or user/behavioral trends do you see that may influence future energy demands of gaming PC systems (upwards or downwards)?

AMD: I’d say four distinct industry trends come to mind, and they pull in different directions:

• Advances in semiconductor process technology will likely continue to improve the power efficiency of new chips over time. These advances should enable future chips to run at lower voltages with less power wasted in the form of device leakage. Meanwhile, growing transistor densities should give us room to create innovative new architectures that extract more performance from each joule of energy consumed. If you look at what’s possible now with a low-power, thin-and-light laptop or even a mobile phone, it’s miles ahead of what a high-powered desktop computer could do a decade ago. We’re working to extend this very positive trend into the future.

• Users expect ever-more realistic and immersive experiences. Whether it’s VR or traditional 3D gaming using high-quality render settings and high-resolution displays, gamers are always looking to push the envelope. As a result, the temptation is always present to push to higher power levels in order to achieve higher performance and better visuals.

• Gaming PCs are moving into new thermally constrained form factors, like quiet mini-PCs for the living room and thin-and-light notebooks. In order to remove the wire tethers from VR setups, some companies are even putting powerful gaming systems into battery-powered “backpacks” based on notebook-class gaming hardware. We have to design more capable and efficient GPUs in order to fit into the constraints of these new platforms.

• In recent years, AMD and RTG have played a key role in supporting the development of efficient new APIs (application programming interfaces) such as DirectX 12 and Vulkan. These APIs allow developers to access our graphics hardware more directly, with substantially less overhead. We’re hopeful these improved tools will deliver improved energy efficiency as developers make better use of our chips.

GGN: What effect do you think VR will have on the energy demands of desktop gaming systems, and GPUs in particular?

AMD: Desktop PCs and GPUs have had a pretty well-defined range of power consumption levels for years now. Thanks to efficiency improvements in hardware and software, we expect nearly all desktop gaming systems to be VR-capable in the not-too-distant future. Quality VR experiences will simply be expected, even by casual gamers. We do expect immersive VR to drive demand for high-performance GPUs in the coming years, but that doesn’t necessarily mean energy demand from gaming PCs will increase. Efficiency improvements should allow us to deliver compelling new experiences within current power envelopes.

GGN: Benchmarking approaches and methods that combine the measures of user experience (UXP) and gaming system energy use are clearly a key need in this space. What's your thinking on this? Can you also speak about related industry/marketplace trends?

AMD: Most reviewers today measure GPU performance in terms of average frames per second (FPS), and some measure power consumption in a basic way. There are finer-grained ways to measure performance by looking at the consistent delivery of frames to the display at the proper intervals to achieve fluid animation. Similarly, there are finer-grained ways of measuring GPU energy use over time.

In fact, we have several methods of modulating GPU performance intelligently so that the graphics chip doesn’t generate frames at a faster rate than the display can handle. We’ve also introduced FreeSync displays with variable refresh rates that can maintain quick responses and the illusion of fluid animation at lower performance and power levels.

AMD and RTG would welcome smart new standards for testing image quality, performance, and responsiveness in the context of energy-efficient operation.

Energy Factoid

Fossil fuels are the preferred feedstocks for electric power plants throughout most of the world. Generating the more than 20,000 billion kilowatt-hours consumed each year for all purposes results in emissions of about 13.7 billion metric tonnes of carbon dioxide, for an average emissions factor of about 1.47 pounds of CO2 per kilowatt-hour of electricity.

Our earlier scoping estimate found that about 165 billion kilowatt-hours are used by PC and console gamers around the world each year, corresponding to about 240 billion pounds of CO2, equivalent to that of about 16 million cars. For comparison, the average US passenger car emits about 15,000 pounds per year of CO2.

Outcomes will of course vary widely by locality. Power plants based exclusively on coal emit about one third more than the world average per unit of electricity, while those based all on hydroelectric emit virtually none. Similarly, the choice of gaming equipment and time spent gaming is also decisive. For US conditions, a middle-of-the-road gaming PC used to game only 1 hour per day in the cleanest US region would emit about 350 pounds of CO2 each year, while an that used by typical World of Warcraft players is about four times as much.

Research Results

Other dimensions of this element of our research program include segmenting the market in terms of user behavioral factors such as hours per day in gameplay versus other parts of the duty cycle (web browsing, idle, sleep, off, etc) by type of user and platform. We will report on these findings in future issues of this newsletter.

Notable Industry Activities & Emerging Technologies

While there has been lots of focus on energy-efficient gaming componentry, software solutions offer a similarly significant potential to reduce energy consumption while maintaining or even improving the gaming experience. Some win-win opportunities exist in that there is no cash investment required in order to get these savings. Dynamic Voltage Frequency Scaling (DVFS) is an important part of this, which involves dynamically changing power states to better match the resources actually required by the computing process (e.g., graphics rendering).

Major GPU manufacturers have launched power-management methods to take advantage of the fact that framerates can be varied depending on the level of action in the scene. One set of trials using one of AMD’s tools (Radeon Chill, a subtab of WattMan) found 31% power savings (108 to 75 W) when applied to WoWc, as well as significant temperature reductions (88 to 77C; 190 to 171 F), plus quieter operation. More interestingly, responsiveness was actually improved, probably because there is less congestion (aka “backpressure”) in the pipeline of cached frames (average framerates fell from 125 fps to 62 fps). They note that the level of savings varies by game title.

A third-party account published in The Tech Report measured a power reduction from 250-260 Watts to 160 Watts with Chill activated.

The chart below shows an example for a session of Witcher 3, in which power reductions with Chill were as high as 22% during periods when little or no screen activity was occurring. Conversely, for only a handful of moments was the full defaulted framerate actually required to achieve the desired user experience.

Source: Tom’s Hardware.

Benefits appear to vary widely depending on the application (and type of activity happening within a gaming session). Games defaulted to use exceptionally high framerates, such as WoWc are the best applications.

Good Reads

Estimating the energy use of gaming requires good market data. A lot of the data we see is cursory and its origins ill-defined. Lack of useful documentation is no doubt in part due to the proprietary value of such information, but also to the fact that energy-relevant information hasn’t been the focus of most past market research in this industry. Of particular importance is information on hours of active gameplay.

Fortunately, some in academia do look at gaming markets and published their results in the peer-reviewed literature. We’ve recently come upon one such example. Sheng-Wei "Kuan-Ta" Chen, a Research Fellow with the Institute of Information Science at Academia Sinica (Taiwan) and Director or the Data Insights Research Laboratory has been looking in great detail at the behavior of MMORPG (Massively Multiplayer Online Role-Playing Game) players. One study by Kuan-Ta focuses on the behavior of 7,043 long-term players World of Warcraft. Over the period December 2005 to October 2007, Kuan-Ta identified an average of 3.7 hours of gameplay per day for these users, with the lower 5% playing 0.5 hours per day and the upper 5% playing 8.8 hours per day. Their entire dataset is available to researchers at no cost.

Cumulative Distribution Functions per Tarng et al. 2008

The results are useful not only for estimating energy use of these intensive gamer subsegment, but also in thinking about how to characterize the additional server-side energy requirements for networked games.

Green-up Your Game

• • Tuning up your existing rig: Some GPUs offer "Zero-core" technology which means they can be powered down when the display is off.

  • When buying gear: Avoid bottlenecks: DIY machines often end up with over-spec’ed GPUs that their CPU or display can't even take full advantage of. Right-size components to work together.

More gamer tips here.

Comings & Goings

We hosted a significant gaming console industry outreach event here at LBNL on December 18, 2016. Representatives of all the major console manufacturers participated (Sony, Microsoft, and Nintendo), as well as the Entertainment Software Association and energy expert Jon Koomey, who presented some preliminary research results focused on benchmarking the energy performance of consoles. The productive meeting included an exchange of information about the LBNL research project goals and latest developments in console technology. The meeting was held in LBNL’s new supercomputing facility, which guests had a chance to tour after the meeting. Interaction will continue as the bench-testing phase of our project ramps up.

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You’ll find lots of information about green gaming at our website.

Send feedback and suggestions of topics you'd like to see us cover to: Evan Mills