even low end gfx cards theoretically support 2048x1536 @ 85 hz but in reality most cards cannot sustain a resolution that high.
resolution depends on many factors and gfx card is one of them.
gaming cards that can deliver high performance at 'high' resolution are:
nvidia: gtx 560, 560 ti, 570, 580, 590(dual gpu)
amd: radeon hd6850, 6870, 6950, 6970, 6990(dual gpu)
high performance cards also cost higher.
your choice of cards will depend on your budget, you pc's spec.