Good points. Efficiency isn't actually all that matters; it's total cost versus revenue. Every mining device has some sort of lifetime to it. Its total cost

Good points. Efficiency isn't actually all that matters; it's total cost versus revenue. Every mining device has some sort of lifetime to it. Its total cost is cost of the device itself + (electrical costs + maintenance + cooling) * lifetime. Its revenue is a function of its hashrate. So, all else being equal, if someone makes a mining chip with less efficiency than the best, they simply have to sell the chip for less $/TH. But usually all else _aren't_ equal. Say you're mining in the far northern regions of the planet. You can take advantage of the colder climate to reduce your cooling costs, so you don't have to expend money designing chips and hardware with good cooling. But you can't take advantage of hydro or solar power, so power efficiency becomes more important. Or, let's say you mine near the equator. Now you can probably build out a solar farm and get cheaper power than anyone else. But cooling is a major issue. You have to spend more on good chip packages and thermal designs. On top of that, the design of the chip itself can dictate a lot of cost. For example, when I designed my FPGA miners, I made it so that the FPGAs could be both programmed and communicated with by a single, cheap FTDI chip. This made the boards super simple and cheap. Basically, it's a complex equation that can't be boiled down to simple power efficiency.