The Elder Scrolls V: Skyrim
Our Skyrim run involved running around the town of Whiterun, starting from the city gates, all the way up to Dragonsreach, and then back down again.
Skyrim behaved surprisingly well at 1080p with the "High" preset, so we felt comfortable using that setting across the board. Note that we ran the game with the high-resolution texture patch installed.
There's something funky going on here. The 7700-series cards exhibit considerably more variance than the rest, with lots of spikes and dips in rapid succession through much of the test. That variance was clearly noticeable when we tested—the game felt like it was skipping along instead of flowing smoothly. We saw something similar with the GeForce GTS 450, but to a much lesser degree.
The 99th-percentile results confirm our observations. The Radeon HD 7770 and 7750 have the highest latency thresholds of the pack. Most of their frame-time spikes lie below 50 ms, however, so they're not penalized in our "time spent beyond 50 ms" rankings. We can't say the same for the GeForces, whose more consistent overall frame times were marred by higher occasional peaks.