Bitcoin mining difficulty can change while your equipment continues hashing at the same rate. Expected bitcoin output for a given amount of work can consequently change. That does not automatically indicate a damaged miner or a pool error. Compare difficulty, accepted contribution, reward components and payment rules over matching periods before explaining a decline.
Mining cooling and ventilation consume energy outside the miner itself. They can also affect operating availability and the time during which useful work reaches a pool. Multiplying a device's advertised watts by an electricity rate therefore gives only part of a site estimate. Define the equipment, measurement boundary, season and allocation method before comparing costs.
A miner drawing more power than its specification deserves a structured comparison. The difference can come from a mismatched operating mode, a shared meter, changing conditions or an actual change in the machine. Start by identifying exactly what was measured. A single watt reading cannot identify a faulty component or establish whether the manufacturer's conditions were met.
An electricity estimate starts with actual power over a defined period, then applies the relevant tariff and other service charges. Three kilowatts for a full day is seventy-two kWh, but one unit price may not reproduce a bill with time bands, tiers or additional fees. Keep energy, cost and mining output separate.
Mining efficiency often expresses energy per unit of computational work as joules per terahash, or J/TH. A lower figure means less energy for the same defined work under matching conditions. It does not alone determine profit, output or purchase suitability. Align algorithm, units, measurement boundaries and operating mode before comparing devices.