Bitcoin’s projected difficulty cut would still leave older S19 rigs short at 5-cent power

Bitcoin miners could earn about 7% more per unit of computing power if a projected difficulty cut materializes, but the relief would leave two older S19 variants needing electricity near 4 cents per kilowatt-hour just to cover machine power.

Hashrate Index’s November 9 snapshot, dated 18:00 UTC, projected a 6.5% difficulty reduction around November 13. The mining data platform put current difficulty at 148.36 trillion and spot hashprice at $31.89 per petahash per second per day. Hashprice measures expected daily revenue from a unit of mining capacity, before expenses.

With Bitcoin’s price, block subsidy and average transaction fees per block unchanged, that projected cut would lift hashprice to about $34.11. It would improve the electricity cushion for miners still operating, while leaving a large gap between older equipment and a more efficient S21.

Lower difficulty increases the probability that a given amount of computing work earns a block reward. Expected revenue per unit of work therefore moves inversely with difficulty when the value of rewards stays fixed.

The scenario calculation divides $31.89 by 0.935, the share of difficulty remaining after a 6.5% reduction. That produces a 7% increase and isolates the retarget’s effect. Actual dollar receipts would also depend on Bitcoin pricing and fees.

Bitcoin recalculates difficulty every 2,016 blocks, using block timestamps to target roughly two weeks. November 13 and the size of the cut remain estimates that can change as more blocks arrive.

Older rigs still need cheaper power

The useful operating test is the highest electricity tariff gross mining revenue can cover. Dividing expected daily receipts by the machine’s daily wall-power consumption gives that electricity-only ceiling. A tariff below the ceiling leaves something toward other expenses; a tariff above it means machine electricity alone exceeds gross revenue.

BITMAIN’s S19 specifications list two model 240-Ca variants at 95 and 90 terahashes per second, both drawing a nominal 3,250 watts at 25 degrees Celsius. Its S21 specification lists 200 TH/s at 3,500 watts under the same temperature condition.

The calculations assume continuous operation at nominal ratings and a 6.5% difficulty cut, with Bitcoin price, subsidy and average fees per block unchanged. They exclude pool fees, separate cooling and site loads, repairs, labor, hosting overhead, financing and equipment costs.

At an illustrative 5 cents/kWh, both S19 variants would still earn less than their electricity bill after the cut. A nominal S21 paying 8 cents/kWh would move from below to just above electricity coverage, leaving a thin cushion of about 10 cents a day before other costs. The two tariffs are illustrative.

The comparison uses each model’s stated power and hashrate. Actual machines can differ: BITMAIN gives the S19 variants hashrate tolerance of plus or minus 3% and wall-power tolerance of plus or minus 5%. The S21 specification gives no numeric tolerance. Each ceiling applies to the specific model and nominal settings shown.

CryptoSlate’s October 14 analysis modeled the electricity squeeze from a projected difficulty increase, while its November 4 report examined a forward market implying little additional mining competition.

The next test is the completed adjustment and hashprice afterward. At the November 9 inputs, the projected cut would expand electricity coverage. Whether that becomes a viable operating margin depends on the actual revenue rate, equipment performance and costs beyond the machine’s power draw.