The Radeon HD 4870 X2 is the fastest graphics card going by a long way.
Don't just take my word for it look here to find out.
http://www.custompc.co.uk/reviews/604626/ati-radeon-hd-4870-x2.html
http://www.techradar.com/products/c...ics-cards/ati-radeon-hd-4870-x2-449317/review
http://www.extremetech.com/article2/0,2845,2327863,00.asp
Don't just take my word for it look here to find out.
http://www.custompc.co.uk/reviews/604626/ati-radeon-hd-4870-x2.html
http://www.techradar.com/products/c...ics-cards/ati-radeon-hd-4870-x2-449317/review
http://www.extremetech.com/article2/0,2845,2327863,00.asp