I bought today the s4 and about one month i buy again 2 machines. I dont know what's the problem. The miners what i have from them work perfect and after next week i make something like 2.5 btc a month. so not bad with my 5 a 6 th/s
No problems expect that, all the BTC you send for buying S4 will never com back.
Should consider it as your fee to learn what these things are.
Happy mining looser.
