CUDA on consumer GPUs for workloads that execute efficiently on those architectures can provide about 2x benefit in energy efficiency and somewhat bigger in acq

CUDA on consumer GPUs for workloads that execute efficiently on those architectures can provide about 2x benefit in energy efficiency and somewhat bigger in acquisition cost, provided there is enough work at each stage of your algorithm to amortize kernel launch latency and PCIe transfer latency and bandwidth. If you buy server-grade GPUs, the cost proposition is similar to power -- at best ~2x benefit.