The Elder Scrolls V: Skyrim
Our test run for Skyrim was a lap around the town of Whiterun, starting up high at the castle entrance, descending down the stairs into the main part of town, and then doing a figure-eight around the main drag.
Since these are pretty capable graphics cards, we set the game to its "Ultra" presets, which turns on 4X multisampled antialiasing. We then layered on FXAA post-process anti-aliasing, as well, for the best possible image quality without editing an .ini file.
The plots above show the time required to render the individual frames produced during our 90-second test run. If you're unfamiliar with our fancy new testing methods, let me direct you to this article, which explains what we're doing. In a nutshell, our goal is to measure graphics performance in a way that more fully quantifies the quality of the gaming experience—the smoothness of the animation and the ability of the graphics card to avoid momentary pauses or periods of poor performance.
Because Skyrim is a DirectX 9 game, it's one of the few places where our representative of older GPU generations, the GeForce GTX 280, is able to participate fully. However, as you can see, the GTX 280 is slow enough to have earned its own plot, separate from the other GeForces. Our decision to test at 2560x1600 with 8X AA and 16X aniso has laid low this geezer of a GeForce; its 1GB of RAM isn't sufficient for this task, which is why it's churning out frame times as high as 100 ms. We had the same video memory problem with our Radeon HD 5870 1GB card, so we swapped in a 2GB card from Asus to work around it.
You can tell just by looking at the plots that the Radeon HD 7970 performs well here; it produces more frames than anything else, and not a single frame time stretches over the 40 ms mark.
The fact that the 7970 produces the most frames in the plots should be a dead giveaway that it would have the highest average frame rate. The newest Radeon reigns supreme in this most traditional measure of performance.
This number is about frame latencies, so it's a little different than the FPS average. This result simply says "99% of all frames produced were created in less than x milliseconds." We're ruling out the last one percent of outliers in order to get a general sense of frame times, which will determine how smoothly the game plays.
I'll admit, I had to stare at the frame time plots above for a little while in order to understand why those two GeForces would have a lower 99th percentile frame latency than the Radeon HD 7970, which looks so good. The culprit, I think, is those first 150 or so frames where all of the cards are slowest. That section of the test run comprises more than 1% of the frames for each card, and in it, the GeForces deliver somewhat lower frame latencies.
Now, a difference of two milliseconds is nearly nothing, but those opening moments are the only place where the fastest cards struggle, and the GeForces are ever so slightly quicker there. I do think some focus on the pain points for gaming performance is appropriate. What we seem to be finding over time is that viewing graphics as a latency-sensitive subsystem is a great equalizer. To give you a sense of what this result means, note that a score between 33 and 37 milliseconds translates to momentary frame rates between 27 and 30 FPS. For the vast majority of the time, then, all of these cards are churning out frames quickly enough to maintain relatively smooth motion, especially for an RPG game like this one that doesn't rely on quick-twitch reactions.
Our next goal is to find out about worst-case scenarios—places where the GPU's performance limitations may be contributing to less-than-fluid animation, occasional stuttering, or worse. For that, we add up all of the time each GPU spends working on really long frame times, those above 50 milliseconds or (put another way) below about 20 FPS. We've explained our rationale behind this one in more detail right here, if you're curious or just confused.
In this case, our results are crystal clear. Only the GeForce GTX 280, which doesn't have enough onboard video RAM to handle the game at these settings, struggles at all with avoiding major slowdowns in Skyrim. We've noted in the past that Skyrim performance appears to be more CPU limited than anything else. Don't worry, though. We'll be putting these GPUs through the wringer shortly.
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