I need to re-correct myself. The best card is not the GTX 650 Ti, within the $140 budget, it is the Radeon HD 7850 which I originally linked to. However, shipping adds $7 to the total cost; $147.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202004
Unfortunately, I read the performance chart just a bit too quickly. The stock speed GTX 650 Ti does not have 97% of the OC'ed GTX 650 Ti, it is 72%. The GTX 650 Ti with the 97% performance is another OC'ed GTX 650 Ti.
sourodip :
but he says his budget is 140$ and the best card with 140$ is hd7790 and it is much faster than the gtx 650ti:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125455
Actually, if you look at the performance chart the Radeon HD 7790 has 71% of the OC'ed MSI GTX 650 Ti while the standard speed GTX 650 Ti has 72% of the performance. That means that the Radeon HD 7790 and stock speed GTX 650 Ti are basically tied. The GTX 650 Ti is the better option because of the lower price. $119 after rebate and includes shipping costs, versus the Radeon HD 7790 which you linked to for $144.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814162127
In any case for $3 more than the Radeon HD 7790, you can buy the Radeon HD 7850.