Our high-quality benchmarks are tested using Far Cry 3's Ultra quality preset, with the addition of 4x MSAA.
AMD's Radeon HD 7870 generally hovers under 30 FPS, below our rough target for playability. Meanwhile, the GeForce GTX 660 Ti and Radeon HD 7950 with Boost are only a little bit quicker. Even the powerful Radeon HD 7970 and GeForce GTX 670 are humbled by average frame rates just above 35 FPS. Only the two Radeon HD 7870s in CrossFire and GeForce GTX 660 cards in SLI manage to generate averages in excess of 45 FPS.
Speaking of multi-card solutions, notice that the Radeons achieve higher average results, but suffer lower minimum frame rates. In the frame rate-over-time chart, you can see that the GeForce boards in SLI yield smoother numbers than AMD's cards, which are not as consistent.
None of these cards are able to handle 5760x1080 using Far Cry 3's most demanding settings.
Although the Radeon HD 7970 and GeForce GTX 670 manage playable results at lower detail presets, I don't think we'll see a GPU able to handle this title at its Ultra detail settings using three screens until the next generation of hardware shows up.
We should also mention that we experienced some texture anomalies on the GeForce cards at this detail level. None of the results are playable, so the issue isn't particularly significant. But we did see something similar when Battlefield 3 debuted, requiring a driver revision from Nvidia to fix.