Bitcoin mining all switched over to custom ASICs long ago, and is barely profitable even on that hardware. The GPUs that were used for Ethereum mining can't compete.

For some more background: bitcoin's POW is basically just sha256, which was trivial to port first to GPUs and then to custom hardware. That makes mining a bigger up-front investment and thus more centralized, which is why almost all later coins chose POWs that aren't easy to speed up with ASICs

Bitcoin is using a different hash function. Bitcoin uses sha, which is easy to implement more efficiently in fgpa and asic, which blows gpus out of the world.

Eth thought that was a bad thing, so chose an algorithm that was intentionally difficult to implement in asic. They thought having gpus be the most efficient platform would be more decentralized and be more one person one vote compared to asics. As a result people use gpus for eth.

Thanks. I'm curious, is there a certain class of algorithms that is generally difficult to implement in ASIC but easy to implement in a GPU?

Usually its about how much RAM it needs access to.

Password hashing algorithms (scrypt, argon2, etc) are generally designed to minimize the advantage custom hatdware gives.

> Why isn't that where ETH miners are going?

Mining BTC on a GPU isn't profitable.

You need a dedicated ASIC chip that is far more efficient at the task than a GPU if you want to hope turning a profit mining Bitcoin.

Something like this:

https://www.bitmain.com/

I'm fairly sure that Bitcoin mining just isn't as profitable to mine with a GPU -- it's more cost-effective to use an ASIC designed for that purpose.