RE: Hardware and Project Selection Part 1 - CPU vs GPU
We could do the math right now if you like!
The V100 GPU Accelerator is FP64 orientated, so lets look at the FP64 project MilkyWay@Home. Vortac is the top miner in that project, and it generates him an income of about 180GRC/day. He does this using 6 Radeon HD7970s, which supply 950 GFLOPS of FP64 processing per card. That means the return per day is about 0.03GRC per GFLOP per day.
As the V100 GPU Accelerator has 5120 GFLOPS of FP64, it would have a predicted yield of 162 GRC/day.
Despite those yields between the 6 HD7970s and the single V100 GPU Accelerator being similar, 6 HD7970s would set you back maybe USD$1000, while a single V100 GPU Accelerator is USD$15000. In terms of power consumption the V100 GPU Accelerator is far superior, but the difference in start-up capital required makes it unfeasible.
To get best ROI, especially in the FP64 GPU applications, older hardware is the way to go. Very specific pieces of older hardware, mind you. Research is required.
My Milkyway numbers are actually way down (at least 30%) because of the summer and the latest heat wave here. I had to severely downclock all my GPUs, plus I have to turn BOINC off during the day otherwise it's simply too hot and I have to run my AC at max power all the time.