Why CPUs Fail at Crypto Mining and GPUs/ASICs Dominate

Initially, mining was performed with CPUs, but CPUs contain many general‑purpose components such as branch predictors and register files that do not contribute to hash‑rate.

CPUs also lack massive parallelism; they can run only a few threads, whereas GPUs have thousands of stream processors, prompting the development of GPU‑oriented mining algorithms.

Bitcoin’s proof‑of‑work takes recent transactions plus a nonce and computes a SHA‑256 hash, which is essentially a series of independent integer operations—exactly the workload GPUs excel at.

While a CPU offers only 2‑8 threads with heavy control logic, a GPU can execute hundreds of integer threads concurrently without branching, making it far more efficient for hash calculations.

OpenCL allows these GPU shaders to be used for integer math, and AMD’s shaders provide many times more compute units than comparable CPUs.

Eventually it was realized that even GPUs are limited; ASICs with massive arrays of ALU units can increase hash power by dozens of times, and modern Bitcoin mining now requires dedicated ASIC miners.

Coins such as Litecoin (Scrypt) introduced memory‑intensive operations that reduce ASIC advantage but still rely on specialized mining hardware. Second‑generation cryptocurrencies like Ethereum and Zcash further optimized their algorithms to resist ASICs, demanding high‑bandwidth VRAM and keeping GPU mining viable.

The surge in GPU demand during 2017, driven by Ethereum mining, caused price spikes and shortages.

In summary, CPUs can technically mine, but their low efficiency and poor parallelism make them impractical compared to GPUs and ASICs.