6000 Rupees won't get you a GPU that'll run on high settings for modern games, but will do medium ok at 1080p or under.
I will strongly suggest looking for a ATI Radeon HD 7770/GHz, it will be over 6000 Rupees (shouldn't be by a huge amount) but is the best card out there for the price. It is also supported by your system and won't bottleneck with your CPU, your PSU should most defiantly power it, just make sure it is greater then 300W, 12v and 18A.