One-Sentence Definition
Ethash and Etchash are memory-intensive mining algorithms that require GPUs with large amounts of VRAM, with Ethash being the original Ethereum algorithm (now retired after the merge to PoS) and Etchash being the modified version still used by Ethereum Classic.
Why It Matters for Solo Mining
If you’re thinking about solo mining Ethereum Classic with etchash mining, you need to understand that this algorithm is specifically designed for GPU mining—not ASICs or tiny devices like a NerdMiner. The algorithm’s memory requirements mean you need GPUs with at least 4-5GB of VRAM (and growing) because of the constantly increasing DAG size. For solo miners, this means your hardware requirements are pretty serious, and your expected time to block depends heavily on your GPU hashrate compared to the network’s total power.
How It Works
Both Ethash and Etchash work by requiring miners to load a huge data file called the DAG (Directed Acyclic Graph) into their GPU’s memory—this is what makes them “memory-hard” algorithms. The DAG file grows over time (about 8MB every epoch, roughly every 4 days), which eventually makes older GPUs with less VRAM obsolete. When you mine, your GPU constantly reads random pieces from this DAG file to solve the mining puzzle, which is why having fast memory matters just as much as having a fast processor.
The difference between Ethash and Etchash is pretty subtle—Etchash was created when Ethereum Classic wanted to resist specialized ASIC miners that had been developed for Ethash. Etchash changed some parameters to make those ASICs less efficient, though honestly, ASICs eventually caught up anyway. The core concept is the same: both algorithms force miners to have lots of fast memory, which levels the playing field for GPU miners compared to pure processing-power algorithms.
Example
Let’s say you want to try etchash mining on Ethereum Classic with a single RTX 3070 GPU getting about 60 MH/s (megahashes per second). With the network hashrate around 180 TH/s, you’d have roughly a 1 in 3 million chance of finding each block—making it pure lottery mining. Your GPU would need at least 5GB of VRAM just to hold the current DAG, and you’d probably want to do some overclocking on the memory (not the core) to maximize hashrate, while using undervolting to keep power costs reasonable.