An ASIC Bitcoin miner is designed exclusively for the purpose of mining bitcoin. Though significantly more expensive to purchase, they are far more powerful (higher hash rate) and electricity-efficient than CPUs and GPUs (graphics cards) – used for mining in the early days of bitcoin – and even FPGAs (field programmable gate arrays), which were, in 2011, the most efficient option. According to Mike Murray, creator of The Geek Pub, a $2500 ASIC miner is as powerful as 400 GPUs, or 12,000 CPUs, which would cost $18 million. For reference, as of February 2018, the Bitmain Antminer S9 possessed the highest available hashrate at ~14 TH/s, with an efficiency of ~0.1 Joule per GH/s, and cost $3200 on Amazon, not including the power supply. ASIC for bitcoin mining hardware Mining is now so competitive, and the difficulty rate so high, that attempting to do so without an ASIC is unprofitable. Because ASIC mining hardware is so expensive, ASIC for bitcoin mining is done by companies in thermally-regulated data-centers with access to low-cost electricity. Many of these companies lease part of their mining power as a service.