ksham :
GTX 660 Ti because of CUDA.
This is absolutely the wrong answer. The exact opposite just couldn't be more true. This blind Nvidia fanboyizm is not only tiring but, it can cost people money.
If video editing is important to you will not want to get ANY of the Nvidia 600 series cards. Nvidia has moved away from GPU computing. If you look at the current most powerful offering from Nvidia and AMD the 690 generally flunked those scores (with flying colors), While the 7990 beat out the 690, the Quadro's and AMD's own FirePro's.
http://www.tomshardware.com/reviews/radeon-hd-7990-review-benchmark,3486-16.html Nvidia now does so bad in this category that even the cheapest AMD 7000 series card will beat the best 600 series Nvidia card in any compute type benchmarks that aren't directly related to gaming.
Compute used to be one of Nvidia's strong points. They say they moved away from it on their 600 series cards to focus more on gaming which I think is a mistake.
Although Adobe still doesn't support AMD compute (openCL) for PC's, the newer Nvidia cards are almost as useless with adobe support and Adobe Premiere Pro and AMD have teamed up to bring support for the open standard to Windows with the software's next version.
Articles: http://www.engadget.com/2013/04/06/adobe-premiere-pro-windows-opencl-support/
http://www.anandtech.com/show/6881/opencl-support-coming-to-adobe-premiere-pro-for-windows
So IMO AMD is the only reasonable choice for your new card.
There are other options for AMD's gpgpu compute (openCL) like Vegas Pro 12 that are currently supported. As long as Nvidia continues to hobble it's desktop cards to try to sell more expensive Quadro's more and more video editing software will support AMD's cards, because cuda support for Nvidia's 600 series cards is little better than no support at all!
Here's some more relevant benchmarks specific to the cards you are asking about.
http://www.tomshardware.com/reviews/geforce-gtx-650-ti-benchmark-gk106,3318-14.html
Good luck!
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