The difficulty of mining bitcoins has increased by 2.9% to 40,640,955,017, thus avoiding its first three-period losing streak since 2011.
The rise corresponds with a jump in total network Hash Rate during the past week. It is challenging all-time highs of 330 PH/s, a level which it has been hovering near for two months without seriously breaking it.
Two weeks ago, the difficulty level dropped for a second consecutive period for the first time since December 27, 2012. As of last week, it had appeared that it would again fall from its level of 39,457,671,307, and the hashrate was at a two-month low near 270 PH/s.
The rise comes despite a languishing Bitcoin price, which has actually declined since the previous difficulty adjustment. It is possible that unprofitable miners that left the network have been replenished by a new glut of efficient hardware deemed more likely to generate a positive return on investment.
Guy Corem, CEO of Spondoolies-Tech, an Israeli mining hardware startup that recently secured $5 million in funding, told DC Magnates that some of the growing mining pools are upgrading to more efficient hardware. As an example, he pointed to AntPool, which currently generates roughly 13% of the network's mining power, according to blockchain.info. He says their growth has been powered by the Antminer S5, which yields a hashrate of 1.155 TH/s and a power efficiency of 0.51 J/GH. He added that newer generations of hardware, such as Spondoolies' SP20, SP31 and SP35, are capable of power efficiencies below 0.5 J/GH.
Corem also believes that a lot of SHA256 activity has been restored to the network after being diverted for the mining of GAW's Paycoin.
Overall, 2014 saw the difficulty increase 34-fold, corresponding with a similar increase in total network hashrate.
For 2015, it is expected that a new generation of ASICs will add further efficiencies and may outpace additional bitcoin price declines should they occur.
