The machines we purchase are brand new and under warranty from the manufacturer. We strive to achieve the longest possible machine life through our care and maintenance. Currently, the life expectancy is expected to be somewhere between 6-10 years. We are able to extend this life by about 4 additional years by cooling in mineral oil etc. The ultimate amount of payback is determined by several factors. The difficulty of mining, the price of BTC, halving and the average hashrate performance of your machine (this is the only factor we can influence).
