While the Ethereum network is preparing to start shifting to proof-of-stake (PoS) consensus, some mining devices might soon stop supporting ETH mining at all.

Bitmain’s Antminer E3, once the “world's most powerful” hardware for mining Ether (ETH), will allegedly stop Ethereum mining in April 2020, according to a Feb. 24 report by altcoin mining pool 2Miners.

Users started reporting a sixfold hashrate drop on Antminer E3 mining rigs on ETC pool last week

2Miners revealed the news after its team requested Bitmain to comment on the recent issues with Antminer E3 performance involving Ethereum Classic (ETC) — an open-sourced blockchain platform that derived from Ethereum hard fork in 2016 after the DAO collapse.

On Feb. 21, 2Miners started receiving first reports on significant deterioration on Antminer E3 mining rigs performance on ETC pool. According to 2Miners, some users reported a sixfold hashrate drop on Antminer E3 — from the factory-declared hashrate of 180 MH/s to as low as 30 MH/s.

Bitmain reportedly confirmed that the issue was caused by DAG growth

Following an internal investigation, 2Miners managed to find out that all global ETC pools were reported the same drop in hashrate. At the same time, Antminer E3 was still performing fine on Ethereum pools, 2Miners said. The team immediately suggested that the issue was likely to be connected with directed acyclic graph (DAG) — a file that is generated every new group of 30,000 blocks known as a mining epoch.

When mining Ethereum, each GPU requires a big file called DAG at the start of the mining process, 2Miners elaborated. As DAG files grow each 30,000 blocks, or mining epoch, the memory capacity has apparently reached its limit.

Following a request to Bitmain helpdesk, 2Miners was reportedly able to confirm that the growth of DAG files limited the usage of Antminer E3 for mining ETC. According to Bitmain, Antminer E3, which is an ASIC miner, still contains a 4GB video card for mining, while the DAG file is approaching the threshold.

Bitmain reportedly said:

“[...] Antminer E3 is a 4GB video card. E3 is related to ETH algorithm, and DDR capacity is up to the upper limit, so E3 will not be able to continue mining. The meaning is E3 only can mine until January 2020, then will not mine again.”

Current DAG size for ETH, ETC and Expanse. Source: Investoon.com

According to 2Miners’ calculations, Antminer E3 should terminate Ethereum mining roughly on April 8, 2020. According to the mining pool, the current Ethereum Classic mining epoch is 328 while it is still 318 for Ethereum. According to the DAG size calculator data, the DAG size for Ethereum accounts for 3.48 GB, while the one for Ethereum Classic amounts to 3.56 GB at press time.

Released by Chinese mining giant Bitmain in April 2018, Antminer E3 was touted as the “world's most powerful and efficient EtHash ASIC miner.” As reported previously, Ethash is the Proof-of-Work (PoW) hashing algorithm used by Ethereum and a variety of other altcoins such as ETC. The release of Antminer E3 came amid the Ethereum community suggesting the possibility of a hard fork in the ETH protocol to invalidate ETH ASICs.

As the Ethereum blockchain is expected to shift from its current PoW consensus algorithm to PoS soon, the block validation function is poised to be given from miners to special network validators. In an interview with Cointelegraph on Feb. 19, Ethereum co-founder Vitalik Buterin said that the first phase of Ethereum 2.0 will be released later in 2020.