Ultimately moving data is the prime power consumer in a data center, so unless you are somehow drastically reducing the amount of data movement, you are not going to get drastic energy savings. This remains true even inside systems and CPUs, fast and wide buses and caches require lots of power, the main power cost in wide SIMD (AVX-512 vs. AVX2) isn't the computation itself, it's getting the data to and from the ALUs.