Corsair vs is crap.go for Antec.
And I think u meant ddr4 right? Cuz i3 7100 doesn't support ddr3.
Look for a better case from corsair, Antec, cooler master from mdcomputers.in if u r from India.
Might I suggest u to switch to g4560 cpu on a b250 mobo if u r tight on budget or ryzen 1500x on a b350 mobo if u have some cash? Cuz the g4560 b250 combo is a better deal than the i3 on a bios update pending h110
I would also recommend going with a 2x4GB matched kit of ram instead of the 1x8GB stick.It enables dual channel access to the memory and therefore improves performance.
finding another 1x8GB stick that will work well with your existing stick is problematical at best and impossible at worst. Even if you get the same make, model, speed and timings, the more time between when the first stick was made and the second works against you. They sell matched sets for a reason. YMMV! Good Luck!