Confirmation of transactions on existing bitcoin and creation of new bitcoins for entering into circulation require enormous computing power, which has to work constantly. This computing power is provided by the so-called mining rigs, which are managed by miners. Bitcoin miners compete with each other to add the next block of transactions to the overall bitcoin chain. This is done by "hashing" - combining all Bitcoin transactions occurring within the last ten minutes, and trying to encrypt them into a block of data, which also coincidentally has a certain number of consecutive zeros in it. Most trial blocks generated by hashing miners do not have this target number of zeros, so they make small changes and try again. A billion attempts to find this "winning" block is called GH, and Mining rig is estimated by how many GH it can perform per second, denoted by GH / sec. The winning miner, who was the first to create a cryptologically correct block of Bitcoin, immediately receives a reward of 25 new bitcoins - the reward at the time of writing was about 15 750 US dollars. This competition among miners with the award is repeated again and again every ten minutes or so. By the beginning of 2014, more than 3,500 bitcoins a day, equal to about $ 2.2 million a day, had been generated. With so much money on the bet, miners supported the rapid arms race in mining rig technology to improve their chances of winning. Initially, bitcoins were mined using a Central processor (CPU), a typical desktop computer. Then in order to increase the speed the chip of a specialized graphics processing unit (GPU) in high-end graphics cards was used. Then the microprocessor with programmable gate array (FPGA) and then the chip of specialized applied integrated circuits (ASIC) were used. ASIC technology is the pinnacle of the line for bitcoin miners, but the arms race continues with the advent of different generations of ASIC chips.