WHAT ARE ASICS?
We’ve focused most of our efforts on the description of mining with GPUs, but originally Bitcoin was designed to be mined using CPUs. It just so happened that with GPUs becoming increasingly programmable, software developers figured out they could get 10, 100, or maybe even 1,000 times the performance of a CPU by doing the calculations on a GPU.
But GPUs aren’t optimized for doing just cryptographic hashing calculations—there’s a whole bunch of extra stuff for textures, 3D graphics, anti-aliasing, ray tracing, and so on.
What if you stripped out all of those unnecessary capabilities and focused on creating a chip that was only good at one thing: cryptographic hashing? It would be faster than a GPU, potentially mining even more Bitcoins! Not surprisingly, lots of others felt like this was a good idea as well.
The result is called an ASIC, Application Specific Integrated Circuit. Technically, a GPU is a type of ASIC, it just happens to be focused on graphics work, while a CPU is a general-purpose ASIC for x86 architectures, or ARM, or whatever. Bitcoin ASICs focus on boosting SHA256 hashing rates as high as possible. Current ASICs can perform somewhere around 1,000 times more hashes per second than even the best GPUs, using a similar amount of power.
There was also an intermediate step between GPUs and ASICs: the FPGA (Field Programmable Gate Array). FPGAs are reconfigurable silicon that can be updated to run different algorithms. There was a brief span of time when FPGAs were used for Bitcoin mining, offering about 10 times the performance of a GPU in the same power envelope, but it wasn’t long before fully custom ASICs replaced FPGAs for most hashing algorithms.