Coarse rule-of-thumb: running on Geforce class GPUs you can get up to 5x, maaaybe 10x the performance per dollar as compared to a top-line CPU. Assuming your problem scales well on GPUs, many problems don&#x27;t. The GTX980 is actually a great performer. For Tesla class systems like the K40 it&#x27;s a lot closer to equal with the CPU on performance&#x2F;$ (they&#x27;re not much faster than the GTX980 but a lot more expensive). But you can get an edge with the Teslas when you start comparing multi-GPU clusters to multi-CPU clusters, since with GPUs you need less of the super-expensive interconnect hardware. (You&#x27;re not going to put GTX cards in a cluster, you&#x27;d have massive reliability problems.)<p>IMHO, the guys showing 100x speedups on GPUs are Doing It Wrong; they use a poor implementation on the CPU, use just one CPU core, consider a very synthetic benchmark, or a bunch of other tricks.