Around 2012/2013, miners started to use GPU or FPGA mining rigs. Shortly after, in mid 2013, a large number of ASIC mining rigs launched. From July 2013, network-wide total hashrate surged due to the large number of ASIC mining rigs put into operation. Based on the average hashrate in July 2013, all CPU mining rigs were unable to generate positive revenue, and FPGA mining rigs were close to zero return.