Ethereum Classic Hard Fork to Change Cryptocurrency Mining Algorithm

In October 2020, Ethereum Classic miners got a pleasant surprise. ETC will enable cryptocurrency mining on 3GB GPUs (relatively old models). Plus, ASICs as well as NiceHash will not support ETC mining anymore.

All of it is going to be possible thanks to the Thanos hard fork at the end of November. Let’s see what to expect from it.

The reason Ethereum Classic took such drastic measures is several 51% attacks in August 2020. For example, at the beginning of that month, ETC users suffered from one of the biggest splits in the network. As a result, around 3500 blocks became orphans, while miners wasted a lot of operating hours.

ETC has come up with the crypto security plan introducing the new mining algorithm. This would also help distinguish Ethereum Classic from Ethereum that uses the same mining algorithm. Since ETC is not the dominant coin of the Ethash algorithm, hackers could easily rent power from Nicehash to attack the network. After all, Ethereum Classic is not as big as Ethereum.

Overall, ETC has benefited from the attacks. The network will change the mining algorithm, enable mining on 3GB and 4GB GPUs by decreasing DAG size, and secure the network by increasing the hash rate. The changes are going to be implemented on November 28.

Ethereum Classic exchange rate has increased by 17.7% over the last week. Here is a 7-day ETC rate chart.

When to Expect Ethereum Classic Hard Fork

The new ETC hard fork is called Thanos. It will implement the EСIP-1099 proposal. The hard fork is going to occur at block 11 700 000. The network is expected to reach it on November 28. It could happen a little earlier or later, but the most probable date is this one.

The main goal of Thanos is to decrease the DAG file size. This will enable 3GB and 4GB GPUs to keep mining Ethereum Classic and ensure the network security.

The DAG file is a special data block that allows users to mine cryptocurrency and earn from it. The DAG file is loaded to the GPU memory and increases with time when epochs change. When the DAG size approaches the size of the GPU memory, the latter is unable to operate, and so mining stops.

ETC wants to bring the DAG file from epoch 390 to 195. As a result, the file size will decrease and old GPUs will be able to load DAG and operate properly. Plus, Ethereum Classic is a reputable project with a long history, so miners won’t have to question its profitability. Unlike newly created crypto projects, there is no way for it to disappear in a few days.

Here is what ETC developers are saying.

At current epoch (372) the DAG size is 3.91 GB. 4GB GPUs are getting obsoleted while they still make up a significant amount of ethash hashrate. Activating this change at epoch 376 (for example), would reduce the DAG size from 3.94GB to 2.47GB. With the reduced growth rate, 4GB GPUs will remain supported for an additional 3+ years.

The DAG size will increase at a lower rate. Previously, epochs on Ethash changed every 30 000 blocks, with the DAG file size increasing with each new epoch. After the upgrade, it will change every 60 000 blocks. Thus, the DAG file size will grow more slowly.

Ethereum Classic: New mining algorithm

The hard fork is also going to change the mining algorithm from Ethash to Etchash. Etchash is a modified Dagger Hashimoto algorithm that ETC will use from now on. As the ETC developers say on GitHub, it is comparable in its behavior to Ethereum foundation’s Ethash but allows for the long-term viability of GPU mining with cards that have low memory (3GB, 4GB, 6GB) available.

This will be possible thanks to the decrease in the DAG size.

The algorithm change will also free the network from ASICs. Etchash is a modified version of Ethash with new changes integrated into it. So existing ASICs will not be able to process the new algorithm, as they can work only with predefined parameters. The hash rate will be distributed among GPU owners, and so computing power will be less centralized.

Etchash was created by Luke Williams. He described the algorithm in September 2020.

How to mine Ethereum Classic after Thanos Hard Fork

Ethereum Classic miners shouldn’t expect any issues after the hard fork. Many mining software developers have already updated to support the fork. Plus, mining devices support the so-called auto-switch (they will automatically switch to the new algorithm).

Here are the settings for mining devices to mine Ethereum Classic after the upgrade. They are specified for the cryptocurrency mining in the 2Miners pool.

Here is a bat file for T-Rex. Autoswitch is supported.

t-rex.exe -a etchash -o stratum+tcp://etc.2miners.com:1010 -u 0x00192Fb10dF37c9FB26829eb2CC623cd1BF599E8.RIG_ID -p x pause

Here are the settings for Gminer. It also supports auto-switch.

miner.exe --algo etchash --server etc.2miners.com:1010 --user 0x00192Fb10dF37c9FB26829eb2CC623cd1BF599E8.RIG_ID

Here are the settings for lolMiner. Auto-switch is again supported.

lolMiner.exe --algo ETCHASH --pool etc.2miners.com:1010 --user 0x00192Fb10dF37c9FB26829eb2CC623cd1BF599E8.RIG_ID pause

PhoenixMiner 5.3 also supports auto-switch.

PhoenixMiner.exe -pool etc.2miners.com:1010 -wal 0x00192Fb10dF37c9FB26829eb2CC623cd1BF599E8.RIG_ID -coin etc

Remember to replace the address with your own to receive rewards. All miners listed above support the auto-switch option. That means that you could set them up before the fork and they should continue mining after the work without any problems. This archive contains all the latest mining software versions. The archive password is 2miners (lower case, no spaces).

The Future of Ethereum Classic Mining

According to the GPU statistics on HiveOS, 45% of AMD graphics cards have 4GB of memory.

It means that once the DAG file in the Ethereum network reaches 4GB, many users might not want to keep mining in the zombie mode and the like, and so they might switch to Ethereum Classic. As a result, ETC mining profitability will go down, as the fixed block reward will have to be distributed among many more users.
It will happen more or less on January 1, 2021. Even though ASICs are leaving the network, the ETC profitability may decrease.

However, if the fees in Ethereum increase and become like in August, 4GB GPU owners may want to keep mining ETH. At least for a couple more months.


Ethereum Classic hard fork is an important step in the cryptocurrency development. It will protect the network from potential 51% attacks, change the mining algorithm, and make ASICs useless. Plus, it will allow the owners of older graphics cards to earn by mining the reputable cryptocurrency.

There is a chance that mining profitability may go down due to these changes, but it is only a hypothesis. So for now, let’s stay positive and be happy for ETC fans, as the ETC security plan is coming into effect.

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