The Elder Scrolls V: Skyrim
We'll start with Skyrim since the outdoor area we tested proved to be particularly difficult for the Radeon, with a number of hiccups disrupting the flow of the animation. This test scenario was the subject of our slow-motion video comparison illustrating the problem. Below is a video showing the route we took during each test run.
Above are plots of the frame rendering times for each card throughout one of our five test runs. You can click on the buttons to switch between the Radeon HD 7950 with the two driver revisions and the GeForce GTX 660 Ti. (And yes, I have changed the look of our plots a bit. Some folks liked the idea of thicker lines, but I worry that they visually overstate the presence of latency spikes. Squint if you must, but I think this is a better way.)
You can see the difference between Cat 12.11 and 13.2 quite easily in these plots. With Cat 12.11, the Radeon's frame times look more like a cloud than a line, and there are intermittent spikes to 50 milliseconds or more. Switch over to 13.2, and the line becomes much tighter, with less overall variance and only an occasional spike above 20 ms. The GTX 660 Ti's line looks tighter still, but it also includes a handful of higher-latency frames.
We can zoom in on a small portion of the test run in order to get a closer look at those frame rendering times. You can see how the 7950's frame times have grown more consistent—and, notably, the high-latency frames have been squelched—with the driver update.
The improvement here is easily perceptible while play-testing the two driver revs. The motion feels much smoother overall with Catalyst 13.2, and little things, like the plants swaying as you walk, become appreciably more fluid.
Interestingly enough, Cat 13.2's improvements don't move the FPS average even a single frame per second. Look at the frame time plots and you can see why: with both drivers, the Radeon HD 7950 produces about 4250 frames over the course of our 60-second test run. Thus, they both average out to the same number of frames produced per second. That fact may tell you all you need to know about the value of FPS averages.
For what it's worth, the "minimum FPS" results that some benchmarks report aren't much help, either, because they average frame times over one-second intervals, and that's just too long a time window to capture important differences. In this test, for instance, the median FPS minimum from five runs with Cat 13.2 is 59 FPS. The same figure for Cat 12.11 is 58 FPS. Yet the slowdowns with Cat 12.11 are very real and perceptible.
Happily, we can capture the impact of the improvements in Cat 13.2 with our latency-focused metrics, including the 99th percentile frame time. This number is just the cutoff point below which 99% of all frames were rendered. The lower the number, the better overall frame rendering picture for the solution being tested. With the new driver, the Radeon HD 7950 comes very close to matching the GeForce GTX 660 Ti.
A look at the "tail" of the overall latency curve even better demonstrates the improvement with Catalyst 13.2. The new driver is quicker for the final 25% of the frames rendered, and it's substantially better for the last 5-7% of frames that prove most time-consuming to render. As a result, the GeForce's advantage in this test has essentially vanished.
Our final latency-sensitive metric tracks frames that take an especially long time to produce. The goal is to get a sense of "badness," of the severity of any slowdowns encountered during the test session. We add up any time spent rendering beyond a threshold of 50 milliseconds. (Frame times of 50 ms are equivalent to a frame rate of 20 FPS, which is awfully slow.) For instance, if a frame takes 70 milliseconds to render, it will contribute 20 milliseconds to our "badness" index. The higher this index goes, the more time we've spent waiting on especially high-latency frames, and the less fluid the game animation has been.
With Cat 13.2, the Radeon HD 7950 delivers fluid animation throughout the course of our test scenario, with only a tiny 10-millisecond blip spent beyond our threshold. That outcome tracks well with our subjective sense that Skyrim smoothness has increased substantially.
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