Ok, but your advice, should i consider to try to sell my 1.6TH CoinTerra, or just to upgrade with some more hardware and continue earn?
You should look closely at how you're actually paying for your electricity - the Cointerra rig is'nt know for it's power efficiency and from what I understand it's close to 1.2 Joules per gigahash, that equates to $5 per day (or $150 per month), assuming you're paying the US average cost of 11cents per kilowatt hour. If you live in the UK you'll pay almost twice that, and the problem with electricity costs is that you have no control over them, (and they will almost certainly never go down), so it's a fixed cost per month to run your miner. As the difficulty goes up, your earnings drop and the cost of electricity becomes a larger portion of your gross income, eventually reaching the stage where you get no profit. At current BTC value this would occur approximately when the difficulty is 10 times what it is now, or the network hash rate hits 500PH. A more efficient rig, say at 0.7 Joules per gigahash would save you $42.50 a month. If the plans that Asicminer has for adding capacity with their new chip come to fruition then it could happen pretty fast, possibly by the end of this year (although it's unlikely)
And of course it depends on what you can sell your rig for, Cointerra dropped their prices recently.
Don't know if this helps or confuses you more, but good luck anyway.
