While AMD has been busy digesting ATI, Nvidia's share of the market for so-called discrete graphics chips has grown to 65% in the third quarter of this year, up from 50% two years ago, according to market tracker Jon Peddie Research.

FORBES: AMD Springs Spider On Market

Nvidia faces challenges in the graphics market from players like Intel and AMD , which are increasingly providing integrated graphics chips to PC makers that reduce the need for separate (discrete) graphics cards.

FORBES: Nvidia Deserves To Gain At Least 15%

With the launch of its Rodeon chips, AMD witnessed a considerable rise in its market share in discrete notebook graphics, registering an increase in share from 38% in 2007 to 48% in 2011, whereas Nvidia witnessed an equivalent drop in its share during the same period.

FORBES: AMD Not Worried As Nvidia Notches New Macbook Pro Win