Sell your S1 as soon as possible, they never make ROI. You eventually lose money. Even S5's make ROI very hard, S1's are antiques now.
Bah, for you. At 0.06 they are still profitable for me and they will continue to be for quite a while. The BTC at the moment is so high, anyone with decent electricity rate can pretty much mine anything and profit.
It's impossible to ROI even you have free electricity. I wonder how do you calculate that and turn into profitable?
What are you talking about? At free electricity, they do 10$ per month, if you buy 10 for 200$, then you have 2 months ROI.
Mines are already paid back and ROI'd a couples of time, now at 0.06$/kWh, they still profit 2$ per month, clearly not much, but since i'm using them to heat my bedroom, this is pretty chill and they make 0 noise with the 17 dB 70CFM fan i have on them.
140GH/s @1.15J/GH