At that budget, I would suggest yoy an AMD build. As far as I know, gaming is your prime objective, go with a more powerful GPU and settle with a cheaper CPU. Here is a great build for that budget-
CPU-AMD FX 6300 Rs 7790.
Mobo-ASUS M5A78L-M LX V2 Motherboard. Rs 3293.
Ram- G. Skill Ddr3 1600Mhz Cl9 Ripjaws X RAM 1600MHz 2x2GB, Rs 3800.
HDD- WD Blue 1 TB. Rs 4048.
PSU- Corsair VS 550. Rs 3250.
Cabinet- Antec X1. Rs 2350.
GPU- Sapphire AMD/ATI Radeon R9 270X with Boost OC 2 GB 2 GB DDR5 Graphics Card. Rs 16300.
Total- Rs 40831.
And you are ready for 1080p High/Ultra gaming.