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Forza Motorsport 7
Let's kick things off with a new addition to our test suite. Forza Motorsport 7 is the latest big-budget racer from Microsoft and Turn 10 Studios, and it offers gorgeous renderings of a variety of exotic auto fauna. Even better, the Xbox Play Anywhere-ready Forza uses the DirectX 12 API to do its thing, so it gives us a look at cutting-edge API performance. To that end, I cued up max settings at a 4K internal resolution.


Forza generally runs swiftly on our test subjects, though all of the GP104-powered cards in this bunch exhibit some minor hitching. Folks hoping for some console magic to transfer from the Xbox One to our Radeons are left wanting, though, as both RX Vega cards finish midpack (albeit in a tight field).


These "time spent beyond X" graphs are meant to show "badness," those instances where animation may be less than fluid—or at least less than perfect. The formulas behind these graphs add up the amount of time our graphics card spends beyond certain frame-time thresholds, each with an important implication for gaming smoothness. Recall that our graphics-card tests all consist of one-minute test runs and that 1000 ms equals one second to fully appreciate this data.

The 50-ms threshold is the most notable one, since it corresponds to a 20-FPS average. We figure if you're not rendering any faster than 20 FPS, even for a moment, then the user is likely to perceive a slowdown. 33 ms correlates to 30 FPS, or a 30-Hz refresh rate. Go lower than that with vsync on, and you're into the bad voodoo of quantization slowdowns. 16.7 ms correlates to 60 FPS, that golden mark that we'd like to achieve (or surpass) for each and every frame For powerful graphics card like the GTX 1080 Ti, it's useful to look at the 8.3 ms threshold. That corresponds to 120 FPS, the lower end of what we'd consider a high-refresh-rate monitor.

Thanks to one big hitch near the beginning of our test run, the GTX 1080 makes a brief appearance in our 50-ms and 33-ms baskets. Even so, the spikiness exhibited by GP104 cards doesn't translate to more than a second spent past 16.7 ms for any of this bunch. The RX 580, on the other hand, runs into enough trouble to spend eight seconds of our one-minute test run working on tough frames that drop its instananeous frame rate below 60 FPS. We have to click over to the 8.3 ms mark to really tease out any differences between our high-end contenders. There, the GTX 1070 Ti narrowly leads the RX Vega 64 and RX Vega 56, while the GTX 1080 turns in the best performance of anything save its GP102-powered cousin.