Raghav Castro :
can u suggest me in NVIDA AND ASUS which can suitable to work to multimedia work i.e video & audio editing .....
Most multimedia editing programs either use the CPU only, or the graphics card slightly. For example, in some Adobe programs a GTX650 does accelerate but a GTX780 which is far more expensive might be only 5% faster.
The amount of DDR3 memory is far more important to some programs. If unsure I suggest 16GB. It's going to vary quite a lot between the program and size of video you edit.
As for the graphics card, a GTX750Ti is likely the best choice unless you game, in which case I recommend the GTX770 if that's in your budget.
The Asus GTX750Ti is roughly $170 I believe, and the Asus GTX770 is $340.