The Hardware/Software Landscape
By mid-October 2019, the Bitcoin mining ecosystem had settled into a mature but increasingly competitive equilibrium. Bitcoin traded near $8,375, with the network hashrate having surpassed 100 exahashes per second earlier in the quarter — a staggering increase from just 40 EH/s at the start of the year. Application-specific integrated circuits dominated the landscape, with Bitmain’s Antminer S17 series and MicroBT’s Whatsminer M20S leading the efficiency race at roughly 50 joules per terahash. Mining operations that had expanded aggressively during Bitcoin’s $13,800 peak in June 2019 were now recalibrating for a market that had retreated over 35 percent.
But beneath Bitcoin’s seemingly stable hashrate trajectory, a different story was unfolding on its most prominent fork. Bitcoin Cash — the fourth-largest cryptocurrency by market capitalization at approximately $4.1 billion — was experiencing significant mining volatility that threatened the economic assumptions underpinning its Proof-of-Work security model. The BCH hashrate in October 2019 was fluctuating in ways that revealed deep structural weaknesses in multi-chain Proof-of-Work systems where miners can freely switch between networks.
The mining pool landscape for Bitcoin Cash was heavily concentrated. According to data compiled by BitMEX Research, BTC.TOP controlled approximately 10.2 percent of BCH blocks, followed by BTC.COM at 9.7 percent, Bitcoin.com at 6.9 percent, and ViaBTC at 6.1 percent. This concentration meant that a small number of pool operators could shift substantial hashrate between Bitcoin and Bitcoin Cash based on relative profitability — and that is precisely what was happening.
Hashrate & Difficulty
The fundamental challenge facing Bitcoin Cash in October 2019 was the convergence of reward-to-difficulty ratios across Bitcoin, Bitcoin Cash, and Bitcoin SV. Research published by Binance in December 2019 confirmed that since September and October of that year, BCH and BSV had seen their respective mining profitability ratios converging with BTC’s — meaning the economic incentive to mine one chain over another was effectively disappearing.
This convergence was significant because Bitcoin Cash had historically offered periods of elevated profitability relative to Bitcoin, attracting opportunistic miners who would switch their ASICs between chains. When BCH profitability exceeded BTC’s by a meaningful margin, miners would flood in, driving up the difficulty. When profitability dropped, they would exit just as quickly, leaving the network vulnerable to prolonged block times until the difficulty adjustment caught up — which on Bitcoin Cash’s original algorithm could take weeks.
Bitcoin Cash had implemented an emergency difficulty adjustment algorithm after the 2017 fork to address exactly this problem, but the October 2019 volatility suggested the mechanism was still insufficient. The hashrate swings were large enough to cause noticeable disruptions in block production times, undermining one of the core promises of any payment-oriented blockchain: reliable transaction confirmation.
Profitability Metrics
For mining operations evaluating where to direct their hashpower in October 2019, the math was becoming increasingly straightforward. Bitcoin at $8,375 with its massive hashrate and difficulty offered thin but predictable margins. Bitcoin Cash at $228.59 offered similar per-megahash returns when its difficulty was properly calibrated, but the volatility introduced an additional risk premium that many operations were unwilling to bear.
Electricity costs remained the dominant variable. At roughly 50 J/TH efficiency, a modern ASIC miner consumed approximately 3,000 watts while producing around 60 TH/s. With electricity prices ranging from $0.03 to $0.06 per kilowatt-hour across major mining regions in China, Central Asia, and North America, the break-even Bitcoin price for the most efficient operations sat somewhere between $6,500 and $7,500 — leaving margins of 10 to 25 percent at current prices.
The profitability calculation for Bitcoin Cash was further complicated by liquidity concerns. While Bitcoin’s daily trading volume exceeded $15 billion, Bitcoin Cash managed roughly $1.2 billion — sufficient for retail miners but posing challenges for large operations that needed to convert significant BCH rewards to fiat or Bitcoin without moving the market against themselves.
Environmental Impact
The environmental conversation around Proof-of-Work mining was intensifying in October 2019, though it had not yet reached the fever pitch that would emerge in 2021. Bitcoin’s estimated annualized electricity consumption was approximately 60 to 70 terawatt-hours — comparable to a mid-sized European country. The rapid hashrate growth throughout 2019 meant that a substantial portion of older, less efficient mining hardware had been retired, which actually improved the network’s energy efficiency per transaction even as total consumption rose.
Bitcoin Cash’s environmental footprint was a fraction of Bitcoin’s — roughly 1.5 to 2 percent — but the volatility in its hashrate meant that the environmental cost per confirmed transaction was highly variable. When hashrate dropped and block times increased, the energy required to confirm each transaction actually decreased, but so did the network’s throughput and reliability. This tradeoff between environmental efficiency and security was an underappreciated tension in the Proof-of-Work ecosystem.
The migration of mining operations from China to more geographically distributed locations was accelerating in late 2019, partly driven by regulatory uncertainty and partly by the search for cheaper, often renewable energy sources. Hydroelectric power in Sichuan and Yunnan provinces remained the backbone of Chinese mining, while operations in Texas, Quebec, and Scandinavia were expanding into flared natural gas and geothermal energy sources.
Strategic Outlook
For the mining industry in October 2019, the convergence of profitability across Bitcoin and its forks represented both a challenge and an opportunity. The challenge was clear: mining was becoming commoditized, with profit margins compressed by increasing competition and stagnant prices. The opportunity was more subtle — as mining economics across chains equalized, the strategic value of mining diversified portfolios of coins increased.
The Bitcoin Cash hashrate volatility of October 2019 served as an early warning for the broader Proof-of-Work ecosystem. It demonstrated that chains sharing mining algorithms with Bitcoin would always be vulnerable to hashrate flight, and that difficulty adjustment algorithms — no matter how sophisticated — could not fully compensate for the economic reality that miners follow profit. The lesson was particularly relevant as the industry looked ahead to Bitcoin’s May 2020 halving, which would cut block rewards from 12.5 to 6.25 BTC and fundamentally reshape mining economics across the entire Proof-of-Work landscape.
For Bitcoin itself, the steady hashrate growth through late 2019 despite declining prices was a powerful signal of network strength. Miners were making long-term capital commitments — purchasing next-generation ASICs, signing multi-year energy contracts, building industrial-scale facilities — based on conviction that Bitcoin’s price would eventually justify the investment. That conviction, more than any single price level, was what underpinned Bitcoin’s security model.
Disclaimer: This article is for informational purposes only and does not constitute financial or investment advice. Mining profitability calculations are estimates based on available data and may vary. Readers should conduct their own research before making any mining or investment decisions.
s17 at 50 j/th was a game changer in late 2019. older s9 rigs became unprofitable overnight below $7k btc
S9 rigs at sub $7K BTC were basically space heaters. whole mining regions in China shut down overnight
the DAA change in Nov 2018 was supposed to fix this exact problem. it helped but BCH still relied on BTC miners switching over when profitable
was mining BCH back then. profitability flips happened multiple times per day. you literally had scripts to jump between pools
bch hashrate volatility was a serious issue. miners jumping between btc and bch chains based on profitability undermines the whole security model of smaller pow chains
the profitability flip was brutal. miners would switch chains mid-day and BCH blocks would slow to a crawl
this is the hashrate mercenary problem fundamental to any small pow chain. BCH was never big enough to sustain dedicated miners
hashbrowns the mercenary miner problem is exactly why BCH never built a real security budget. you cant have hashrate that vanishes every time BTC gets more profitable
hashbrowns the mercenary mining problem is structural for any PoW chain without enough native economic activity. BCH tried to fix it with DAA but you cant engineer your way out of insufficient dedicated hashrate
hashrate mercenary problem is structural for small PoW chains. BCH tried to fix it with DAA but you cant engineer around insufficient dedicated mining
the automated pool switching scripts between BTC and BCH were running on 15 minute intervals. profitability arbitrage between chains became its own micro-economy with dedicated software
and the DAA adjustment couldnt keep up with the switching speed. blocks were coming in 30 seconds or 2 hours depending on which chain was profitable that minute. consensus stability requires miner loyalty which BCH never had
microbt m20s was quietly eating bitmain lunch in 2019. better efficiency, better availability, less drama
whatsminer_og microbt was definitely winning in 2019 but bitmain had the s17 pro which closed the gap later. the real issue was supply, not specs
BCH at 4.1B market cap in Oct 2019 with hashrate that could vanish overnight. POW security only works with enough dedicated miners
S9 rigs mining BCH at a loss below 7k BTC was brutal. watched entire farms in Sichuan go dark overnight when the profitability flip hit
Sulo P. watched the same thing. Sichuan farms had automated scripts flipping between BTC and BCH pools. profitability changed faster than block times could adjust
Whatsminer M20S at 50 j/TH was the turning point. S9 farms that were marginal at 7k BTC became instantly unprofitable and those miners never came back to BCH
S9 rigs mining BCH below 7K BTC was basically space heater territory. entire Sichuan farms went dark overnight when the profitability flip hit
fee_bear_ S9 farms in Sichuan had automated scripts flipping between BTC and BCH pools. the second BTC profitability ticked up, BCH hashrate dropped 40% in minutes
Joona R. the Sichuan scripts flipping between BTC and BCH pools was literally how the DAA got stress tested. chaotic but it worked
Joona R. the Sichuan scripts flipping between BTC and BCH pools wasnt a bug it was the DAA working as designed. the problem is that working as designed still means hemorrhaging hashrate every time BTC blips
Joona R. the Sichuan scripts flipping between BTC and BCH pools wasnt a bug it was the DAA working as designed. the problem is that working as designed still means hemorrhaging hashrate every time BTC blips
Whatsminer M20S at 50 j/TH made the S9 instantly unprofitable for BCH. the hardware efficiency gap was the real killer, not the price action
50 j/TH on the M20S was the nail in the coffin for S9 miners on BCH. hardware obsolescence did more damage than any price chart
Whatsminer M20S at 50 J/TH killed the S9 overnight. farms in Sichuan had hardware worth negative value after electricity. you literally couldnt give S9s away by November 2019
Whatsminer M20S at 50 j/TH destroyed the S9 economics overnight. BCH mining became unprofitable for 90% of hardware before anyone could react. no DAA adjustment fixes that
Whatsminer M20S at 50 j/TH destroyed the S9 economics overnight. BCH mining became unprofitable for 90% of hardware before anyone could react. no DAA adjustment fixes that