My 6850 runs the latest titles on high presets with 60+ fps, no overclocking. Heavy DX9 games are an exclusion which basically includes The Witcher 2, I haven't had any issues otherwise.
I run my games on 1920x1080, I would imagine the Titan to bode far greater performance. Of course there are a few games which might kill the Titan on ultra 1440p
with their artificial filters, think TW2's ubersampling for instance.
Passmark Scores:
Titan = 8401
6850 = 2223
Most of those filters that kill your GPU are due to highly inefficient coding, and honestly they were intended that way. The tent AA they have been raving about over the past 6 months smooths out the jags on HD+ resolutions further but actually:
1 - Decreases overall picture quality as it causes textures to be blurry outside of the primary focus
2 - Highly inefficient
My 6850 is starting to show its age