Radeon Chill: Performance And Power Consumption
FPS: All or Nothing?
Looking at performance alone misses the point of Radeon Chill, but we still want to see how AMD's feature affects frame rates in absolute terms. Just try not to think of this chart as "higher is better," because that's not what we're trying to show.
Right out of the gate, we see the most demanding scene diminishes the impact of Radeon Chill the most, just as we were expecting. Meanwhile, the frame rate drops quite a bit in the sequence with the least amount of motion. That's pretty much what AMD is advertising.
But as we know, frames per second is too broad of a metric to represent performance on its own. Frame time is often much more important, particularly when it comes to measurements that involve smoothness. And Radeon Chill definitely needs to be checked for its effect on frame delivery.
We begin with the first scene, where Geralt is standing still. It's important to note that we dialed in the highest-quality settings, just as a real gamer would do playing The Witcher 3 at 1920x1080 on a Radeon RX 480. No doubt, AMD would have rather have us use a less demanding detail preset to show Chill pumping the brakes on 100 FPS+ performance. Frame times would have looked better in absolute terms. However, we want to represent real-world game play and not some hypothetical case. Our conclusion would have been the same anyway.
Now let's rotate the camera or get Geralt to jump around and throw some attacks. Color starts coming into play, and we can see the rapid performance increase once movement demands higher frame rates (identifiable through lower frame time values).
Dynamic movement is smooth, as it should be, and the already-calculated scenery uses less power.
It's time to run around and deliberately try to force prevent Radeon Chill from having an effect. The two lines track each other closely as performance needs outweigh Chill's proclivity for power-saving.
Let us now compare the frame times as a bar chart, broken up into intervals:
Frame time variance increases as Radeon Chill becomes more active, though this is what we'd expect from a feature designed to relax performance in the name of lower power consumption.
Subjectively, the RX 480's frame delivery is smoother than the bars suggest. It's certainly not ideal, though. We think you'll want a FreeSync-capable monitor to truly maximize what Radeon Chill brings to the table...so long as your realized frame rates fall within the display's variable refresh rate range.
Power Consumption
Of course, the reason for Chill's existence is lower power consumption. And as the chart below shows, our savings is up to 22%. It's no wonder AMD would like to throttle down from 90 to 40 FPS.
In the real world, though, when were you ever seeing 90 or 100 FPS? Unless you're playing StarCraft or Counter-Strike at their highest detail settings, those figures aren't realistic on an RX 480 at 1920x1080. AMD's whitelist has a lot of lush-looking games on it that won't get quite so much benefit from Radeon Chill, since they won't be modulating performance as much as the less-demanding titles.
To go with the stand-still test's frame time benchmarks, we also have power consumption measurements in the same scene, with and without Radeon Chill:
When Radeon Chill is activated, the measured minimum values drop significantly, along with the peaks. As a nice side-effect, noise output drops as well.
Summary And Conclusion
What do you do as a manufacturer when you are constantly being criticized for higher power consumption and lower efficiency than the competition? That's right, you come up with ways to reduce unnecessary work, and when your hardware has the chance to idle (even on a millisecond basis), you seize the opportunity to save some power.
Radeon Chill is not a silver bullet, and it cannot make up for AMD's architectural disadvantages. However, if a game is well-suited to the feature's strengths, then there are clear savings to be had by enabling Chill. This feature does help supported cards run cooler, and thus quieter. There's not much more we could ask for except a longer whitelist or, better still, an option to enable Chill at our own risk for every game, even the ones not yet officially supported. For the time being, AMD's software team is to be commended for the innovation it continues piling onto the hardware.
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