Your posting on the CPU side of the forum...this question has to be posted on the Graphics Card side.
Anyway, no the 7970 is not worth the extra money, although it is more powerful than the 7850. If you can get the sapphire version for Rs, 18,500, then its cool, otherwise you may have to settle for a Asus 660Ti TOP edition.
But keep in mind that only XFX and Asus offer a full no nonsense 3 yr warranty in India (eventhough its through the much hated Rashi peripherals). Sapphire has a 2yr+ 1yr labour only policy. Zotac's warranty is even worse.
When paying 15k+ for a GPU, i'd like to have a nice safe warranty cover for me