Benchmarks: 1920x1200
Increasing the resolution to 1920x1200 on ultra reduced the R9 290X to 60fps – equal to the R9 270X in Crossfire – and the GTX Titan was 13% slower with 52fps. If you intend to average 40fps with these settings, you'll need at least the HD 7970 or GTX 770, though the GTX 670 or HD 7870 might suffice if you're willing to play with 30fps.
Dropping the quality to high allowed the GTX 660 and its Ti version to produce 41fps and 43fps while the HD 7850 fared well with 46fps and the 7870 was even faster at 55fps. To play with a solid 60fps or better on high, you'll have to employ the GTX 680 or R9 270X at minimum.