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Why GPU mining is making a comeback with Grin

However, as the value of certain cryptocurrencies fell, and ASIC mining started to dominate, it quickly became unaffordable to mine on a GPU. Put simply the investment in hardware and electricity didn’t net enough of a return to make it worthwhile. And thus, the era of GPU mining was over, never to return. Or was it?

Grin and bear it

While Bitcoin and Ethereum are perhaps the most famous cryptocurrencies, there are actually 2,534 different currencies on the market. However, despite so many currencies on the market, the recent buzz centres around so-called ‘privacy coins’, which focus on secure and anonymous transactions and aim to address some weaknesses with existing cryptocurrencies. One privacy coin in particular is generating a lot of excitement, and could also signal the resurgence of GPU mining; this coin is called Grin.

Grin is really wizard!

Grin is an implementation of MimbleWimble, which is a blockchain protocol first proposed in 2016 by an anonymous cryptographer named ‘Tom Elvis Jedusor’. This name, along with MimbleWimble and Grin itself are all semi-cryptic references to Harry Potter (see boxout for more).

MimbleWimble is a privacy-by-default blockchain that is designed to be scalable, and the Grin implementation addresses some key concerns with existing currencies. For example, the fact that Grin has no addresses means that transactions cannot be traced or linked back to an individual. You might think this is already true of other currencies, such as Bitcoin. But although a Bitcoin address is anonymous, the blockchain and every transaction is open. This means that individuals could be connected to certain transactions – for example, a purchase at an online retailer that stores personal information about you as a cookie. And once your wallet is linked to your identity, your entire transaction history can be traced.

It’s all Fungible games, until someone gets hurt

Privacy is a crucial factor in ‘fungibility’, which is ensuring that the values of items of the same type are the same. For example, a £1 coin is the same value as every other £1 coin in the world, but a diamond may have a radically different value to another diamond of the same mass, depending on many quality factors. The fact that Bitcoins could be linked to individuals, and perhaps to criminal activity, means that, in the future, Bitcoins with a transaction history may end up being worth less than those with no transaction history.

Grin also dramatically reduces the size of the Blockchain by removing the majority of past transaction information, which means only a fraction of the data is stored compared to other coins. This helps to ensure than transactions won’t become unwieldy, which is a problem that Bitcoin faces, for example.

Grin is also driven by the community and is focused on decentralized development. As Grin developer ‘Yeastplume’ said in a statement1: “We are not driven by profit or corporate interests… We’re open-source and community-driven by design.”

All this sounds completely Cuckoo

As with other cryptocurrencies, transactions are validated and added to the blockchain through the process of mining. For Grin, this involves solving a memory-bound graph-theoretic proof-of-work algorithm called the Cuckoo Cycle, with miners rewarded in currency for their efforts.

Grin will actually launch with two proof-of-work algorithms – a primary algorithm called Cuckatoo, which is ASIC Friendly (AF) and a secondary algorithm that is ASIC Resistant (AR) called Cuckaroo, which can be mined by CPUs and GPUs.

The great news for GPU miners is that, at least initially, 90% of the rewards will be for mining the AR Cuckaroo algorithm. This is intended to slow the growth of ASIC miners and encourage a decentralized mining market. The AR Cuckaroo algorithm will fork every six months to thwart ASIC domination (the AF Cuckatoo algorithm does not fork), but the rewards decrease 3.75% per month until there are essentially zero returns after two years. At which point, a range of ASIC miners should be available to provide competition and maintain decentralized mining.

The rise of the Radeon

However, although GPU mining will eventually tail off, there is a tremendous opportunity for first-movers to take advantage of the high rewards from early mining. Just as long as you have the right hardware. This is where Grin differs to Bitcoin for example, because while Bitcoin’s proof-of-work algorithm is based on SHA-256, which requires a huge amount of processing power, the Grin algorithms are memory bound. In fact, the GPU-friendly Cuckaroo algorithm could require greater than 5.5GB of video memory, while the ASIC-friendly (AF) Cuckatoo algorithm at least 11GB of memory. Extra memory will, of course, make processing Cuckaroo and Cuckatoo even faster.

While most mid/high-end GPUs have at least 8GB of memory, very few have more than 12GB, and 16GB will be required to mine using the 2020 variant of Grin Mean AF Cuckatoo algorithm. A GPU with a 16GB frame buffer could conceivably mine both the GPU friendly and ASIC friendly algorithms for more than 2 years whereas others are limited to just the GPU friendly Cockaroo after the first year.

Mining the latter on GPU, before ASIC miners come to market, means less competition and a higher probability of winning a block reward. But no such GPU exists, at least at an affordable price — or does it?

The money printing machine

Sapphire Technology looks to have a great early-mover advantage thanks to the imminent release of a 16GB version of its Radeon RX570 graphics card. Not only are the Compute Units of the RX570 well suited to mining the Grin algorithm, but with 16GB of memory it can mine both the Cuckaroo and Cuckatoo algorithms. This will allow miners to see-saw between each one as the difficulty swings from back and forth, a process also known as ‘Dual Mining’.

Sapphire will have access to a Grin miner that will port the CUDA miner to OpenCL. Factor in the affordable cost of the Sapphire 16GB RX570 itself, which is a third of the price of competing 16GB cards designed for professional applications, and Sapphire seems to have produced a veritable money printing machine.

Mining on GPU has been a rollercoaster ride over the last couple of years, but with the rise of privacy coins and the huge interest in Grin, 2019 again promises to be a profitable year for GPU miners, providing you move fast and take advantage of the best available hardware.