[IDEA] What about mining on CPUs again?

[2112]

Would it be possible to make a coin that could only be mined if you had SSE instruction set 1,2,3, etc? As far as I know no GPU would be able to decode something that required one of those instruction sets.

This doesn't make sense: the code has to be open source and therefore any competent programmer could rewrite it from SSE/AVX/etc. to the vector instructions of the GPUs. And the GPUs are much faster at single- and double-precision floating point (32-bit and 64-bit).

The thing that handicaps GPU is the extended-precision (80-bit) floating point. It isn't impossible to emulate it on the GPU, its just that the results will be significantly slower and will require significant development effort that will be of little use anywhere else.

There are various quad-float (128-bit) libraries is where the multiple-precision floating point development work is geared.

[mg27341]

The thing that cripples GPUs is the lack of significant memory per thread on the video card.

Have a scheme that uses scrypt and requires 2GB per thread (or even as little as 256MB per thread perhaps) and your quad-core CPU with 8 GB of RAM will beat any video card. The GPU can do many threads, but they aren't very fast. Attach large memory requirements to each thread and the GPU (as well as FPGA and even ASIC) is dead in the water.

[2112]

The thing that cripples GPUs is the lack of significant memory per thread on the video card.

Have a scheme that uses scrypt and requires 2GB per thread (or even as little as 256MB per thread perhaps) and your quad-core CPU with 8 GB of RAM will beat any video card. The GPU can do many threads, but they aren't very fast. Attach large memory requirements to each thread and the GPU (as well as FPGA and even ASIC) is dead in the water.

This is only GPU-defeating. FPGAs will trivially beat that, not to mention an ASIC with eDRAM instead of DRAM. Or there already may be an existing SoC-s with ARM CPU attached to sufficient eDRAM, but almost all of them are under NDA. All of those will massively beat Intel/AMD on power efficiency and easily compete on speed.