Prior to mining, miners generate segments of data known as plots that are saved to the hard-drive. The more plots stored; the faster a miner can mine. With every unsolved block, the miner’s hard-drive will search through the saved plots to estimate a timeframe for which it can mine a block if that block has not been found. Once the hard-drive reads through the plots, it will sit idly until the block can be solved. In theory, this means that HDD mining is incredibly power efficient and can be safely done on a laptop, unlike PoW mining.
