I was about to order the batch 8 but now I am having second thoughts about ROI.
Even with free electricity, the analysis here
https://tradeblock.com/bitcoin/mining/a/JzZtkWrbEJb3LeJj28EoCkshows that I would ROI on August 2016, assuming starting mining on January 2016 and ~5 billion difficulty increase each month (best case scenario). (purchase cost ~$2000, including PSU and customs fees)
Keep in mind that bitcoin halving will be about July 2016.
So why would someone buy a S7?
Speculation on the price of bitcoin rising...if it doubled by the halving, you would probably ROI on it. Either way it's a gamble.
There is no point to buy mining hardware and just hope for a BTC price increase. Just buying and holding BTC is much simpler and safer.
All ROI calculations should assume a stable BTC price . In other words, you should calculate your initial costs in BTC and see how many BTC you will get back. By investing 4.73
BTCfor a S7 + 0.487
BTC for PSU + ~1
BTC for customs fees = 6.217
BTC total, you will probably earn these BTC back by August 2016, just after the halving.
I was about to order the batch 8 but now I am having second thoughts about ROI.
Even with free electricity, the analysis here
https://tradeblock.com/bitcoin/mining/a/JzZtkWrbEJb3LeJj28EoCkshows that I would ROI on August 2016, assuming starting mining on January 2016 and ~5 billion difficulty increase each month (best case scenario). (purchase cost ~$2000, including PSU and customs fees)
Keep in mind that bitcoin halving will be about July 2016.
So why would someone buy a S7?
You are betting on 5% diff increases?
Only with Bitmain throwing shittons of HW out the door are we seeing that much. They won't be putting gear online @ 5% for that many months at least!
First of all, these increases are
monthly increases, not the increase every 2 weeks.
Second, I assumed 5
billion increase each month, not 5% (i.e.
linear increase, not exponential).
These assumptions for difficulty increase are fairly optimistic.
Even with ZERO diff increase. ROI will happen in June 2016.
And remember, these calculations are with FREE electricity!