Hi guys , I'm new here and  I'm noob in bitcoin mining

I'm thinking about start mining I have free electricity

if I buy Antminer S3 about 120$ Used (I think it's cheaper for 1 GH ) I will achieved roi at 3 months

the problem here is : used S3 can support overclocking for long time

and what is term life for S3 normally to dead (with/without overclocking)


THANK YOU ,