Basically it's an automated program which reduces CCX voltage so it's able to run cooler and consume less power, which in turn allows the CPU to boost higher for longer, which is not a surprise given AMD's -very- heavy handed voltage applications. Should be of particular interest with the A520 boards which limit or prevent manual overclocking.
https://www.guru3d.com/news-story/clocktuner-for-ryzen-(ctr-by-1usmus).html
