Without the ability to test triple-monitor resolutions, I had to settle for the largest single resolution at my disposal, a QHD screen's native 2560x1440.
The number of cards worth testing shrinks at this taxing combination of high resolution and Ultra graphics details. Only AMD's Radeon R9 280 and 290X keep their noses above a 30 FPS minimum, while Nvidia's overclocked GeForce GTX Titan delivers a 15-FPS-higher result. It's also the only board capable of approaching a 60 FPS average.
The GeForce GTX 760 would have done better, but it encounters a single valley in its frame rate trace, hammering the minimum result. After testing and retesting, observing the same dip each time, its result stands. Similarly, the Radeon R9 270 and GeForce GTX 660 get hit by rogue dips that push minimums further into unplayable territory.
Frame time variance is a mess in this chart, though if you focus only on the higher-performance cards, it's not as bad. In short, Nvidia's overclocked GeForce GTX Titan is the only option approaching a truly smooth result.