Slush Pool Identifies Bitcoin’s First Overt-AsicBoost Block

Slush Pool said on March 24, 2018 that Bitcoin block 514,882 was the first block mined with active version rolling, the transparent form of the mining optimization known as overt AsicBoost. The block is preserved in Bitcoin’s ledger, while the pool’s contemporaneous announcement attributed the work to Halong Mining hardware operated by a miner in Guangdong, China. That hardware attribution was a claim by the pool, not a fact independently encoded in the block.

What the block demonstrated

AsicBoost changes how specialized mining chips organize repeated SHA-256 calculations. The original technical paper described a way to reuse part of the computation across multiple attempts and estimated an efficiency improvement of approximately 20%. The important distinction in March 2018 was between covert and overt implementations.

A covert implementation varied data connected to the transaction tree in a way that was difficult for outside observers to identify. Overt AsicBoost instead varied permitted bits in the block header’s version field. The method was visible in the resulting header and required coordination between a miner and its pool. The Stratum version-rolling specification documented that coordination: a miner and server negotiate a mask defining which version bits the miner may change, and the miner returns those bits with submitted work.

Block 514,882 therefore mattered less as a routine addition to the chain than as a public proof that a pool and commercial ASIC could use version rolling on Bitcoin’s live network. Slush Pool reported roughly 16 terahashes per second from the device involved. The chain record verifies the block; the pool’s statement is the contemporaneous source for the claimed equipment, location and hashrate.

Why miners and protocol developers cared

Mining efficiency determines how much computation an operator can obtain from a fixed amount of hardware and electricity. An optimization near the scale described in the AsicBoost paper could change unit economics and pressure rival manufacturers to support the same technique. It could also widen an information gap if only a few firms possessed or secretly used it.

That competitive concern had made AsicBoost controversial before March 24, 2018. The overt design offered a different governance tradeoff: it preserved the efficiency argument while making use detectable through version rolling. The BIP 310 specification also made the pool-to-miner interface inspectable rather than proprietary. Neither the block nor the specification proved that adoption would be broad, that realized energy savings would equal the paper’s estimate, or that Halong’s machines would ship at scale.

The milestone also arrived after the AsicBoost patent owner said on March 1, 2018 that it would offer relevant rights under the Blockchain Defensive Patent License. That announcement reduced one legal obstacle to use, but it did not by itself establish market adoption or settle every implementation question.

Market context on March 24

The event landed during a partial cryptocurrency-market recovery. Kraken’s March 24 daily report listed bitcoin at $8,966, up 4.22% under the exchange’s report window, and reported $98 million of BTC trading on Kraken. Those figures describe one venue and its own measurement window; they are not a consolidated global close or total Bitcoin volume.

The price backdrop helps explain why hardware efficiency remained institutionally important even when market attention was dominated by volatility. Miners earned bitcoin-denominated rewards while paying many operating costs in local currency, so both network competition and exchange prices shaped their economics. No evidence in the cited records establishes that block 514,882 moved bitcoin’s price.

What was knowable on March 24

The defensible event-day conclusion was narrow: Slush Pool had announced a first overt-AsicBoost block, and Bitcoin’s public ledger preserved the referenced block. The technical records explained why version rolling could make the optimization transparent. Claims about the DragonMint hardware’s sustained performance, commercial availability and effect on mining concentration still required follow-up evidence after March 24, 2018.