Performance of four GTX 1080 Ti's versus one Tesla V100 for Deep Neural Network training
This link has more realistic benchmarks of 1080ti vs Titan V (same as the V100 but less RAM), using pytorch. Its not nearly the best case scenario of 10x speedups, and seems to be a more modest 20% to 50% boost. This is fairly expected, nVidias grandiose performance claims tend to be only applicable to fairly restricted benchmarks that don't scale well to real world usage. You'd probably get a lot more out of 4 1080ti cards than a single V100 unless you REALLY need a large amount of RAM in a single card.