The higher the resolution, the more the GTX 980's bandwidth limitations come into play...
...but it turns out that Titan X is a capable overclocker too. We added 230MHz to the core clock, 465MHz to RAM and ramped up the power limit to 110 per cent (unfortunately no voltage boost options were available). At 1080p, this only gave us a 13 per cent increase to stock performance, but at 1440p that rose significantly to 18.2 per cent.
And here's where things get really interesting. With the overclock in place, Titan X compares favourably with two GTX 980s operating in SLI - even beating the dual GPU set-up in games like Crysis 3 and Call of Duty Advanced Warfare. The COD situation highlights another advantage of single-chip over SLI - the fact that some games simply don't work properly with it. In truth, a single GTX 980 offers a better experience than an SLI set-up owing to the insane stutter using a multi-GPU set-up incurs.
At 4K, the benchmark comparisons with the GTX 980 SLI set-up really show the card's strengths - frame-rates are competitive but as you can see from the videos (which also track frame-times - more indicative of the actual gameplay experience), the overall consistency in performance is significantly improved. Take Assassin's Creed Unity, for instance. GTX 980 SLI frame-rates are higher than the overclocked Titan X by nine per cent, but it comes at a cost - significant stutter. In this case, we suspect that ACU at 4K is tapping out the 4GB of RAM on the GTX 980, while Titan X has no real memory limitations at all.