ASIC specification sheets are written to sell hardware, and the headline number is almost always hashrate. Hashrate alone tells you very little about whether a machine will earn money. A handful of less prominent figures matter considerably more. Efficiency Is the Number That Counts Efficiency, expressed as joules per terahash, describes how much electricity a machine consumes for the work it does. Two miners with identical hashrate can differ substantially in efficiency, and over a year that difference translates directly into profit or loss. A higher-hashrate machine with poor efficiency frequently earns less than a slower, more efficient one once...