My RX480 card is not Power Efficiency embedded and if its not enabled, any 3D game raise the GPU clock to 1276Mhz without any for good sake need to it. It's more heat and watts drained, but more important, it's a life shortening for the card. People complain about hardware issues, "green screen", "artifacts", and so on, and what cause this? Heat and... Graphics cards these days are disposable like bulb lamps, they are made to work more fiercely that they are engineered for, because high graphics games demands from users an disposable behavior to have things always up to date for enable some fancy feature, so most normally change it before it dies, but me. Power efficiencies implementation give to folks like me more years of usage, and for those who has cards with it embedded the option to disable.
Power Efficiency is imperative, simple as that. I like to play most of the exploring games at 30fps and some more agitated ones at 60fps to follow my monitor (do you read it AMD? 30fps! So why I need 1276mhz all the time or underclock and undervolt my GPU to some fixed value if I had an option that did both on the fly and dynamically?). I'm using the last WHQL driver from 2019 (19.9.2) and everything is fine, but new games are coming and I will be forced to update to 2020 any soon, if I don't rant now I will have nothing interesting later, or at least be sure that I tried.