Here is a another option for you:
Intel Core i3 6100 only chip Rs. 9500 (second hand) (get a cheap cooler for it from the market, should not be more then 500 rs)
6th Generation Processors ( i7 6700 _ i5 6400_ i3 6100 ) Brand NEW Chips
GIGABYTE GA-H110M-DS2 DDR4 Rs. 6500 new
Corsair Value Select Memory DDR 4 2133 Rs. 6200 new
Corsair VS550 Rs. 5400 new
Hdd and gpu you already have
Any casing with the money left over
total: 28100