What Is the Fundamental Difference in Architecture between a GPU and an ASIC That Makes the Latter More Efficient for Mining?

GPUs are designed for parallel general-purpose calculations, having thousands of cores but also non-essential components like texture mapping units. ASICs, however, are purpose-built silicon chips containing only the circuitry necessary for a single, specific task, like the SHA-256 hash function.

This single-minded design eliminates unnecessary overhead. It leads to significantly higher performance and lower power consumption per hash, a measure of energy efficiency.